Uplink data transmission method in wireless communication system and apparatus for the same

ABSTRACT

A method for transmitting uplink (UL) data requiring low latency in a wireless communication system according to the present invention, the method performed by a user equipment comprises transmitting contention PUSCH resource block (CPRB) indication information used for identifying a particular UE and/or particular data to an eNB; transmitting UL data to the eNB through CPRB resources of a contention based PUSCH (CP) zone; and receiving a hybrid automatic retransmit request (HARQ) response with respect to the UL data from the eNB through a physical hybrid ARQ indicator channel (PHICH).

TECHNICAL FIELD

The present invention relates to a wireless communication system andmore particularly, a method for a terminal to transmit uplink data to abase station and an apparatus supporting the method.

BACKGROUND ART

Mobile communication systems have been developed to provide a voiceservice while ensuring mobility of users. The mobile communicationsystem has evolved to provide a data service in addition to the voiceservice. These days, due to explosive growth of traffic, communicationresources are easily running short. Also, since demand for higher speedservices is great, needs for more advanced mobile communication systemsare getting larger.

Requirements for the next-generation mobile communication system largelyinclude accommodation of explosive data traffic, considerable increaseof transmission rate for each user, accommodation of the significantlyincreased number of connected devices, very low end-to-end latency, andhigh energy efficiency. To meet the requirements, various technologiessuch as dual connectivity, massive multiple input multiple output(MIMO), in-band full duplex, non-orthogonal multiple access (NOMA),support for super-wideband communication, and device networking arebeing studied.

DISCLOSURE Technical Problem

The present invention has been made in an effort to provide a method forpreventing collision during transmission and reception of inability ofterminals to estimate an UL data channel due to selection of the sameCPRB and an error correction response (HARQ ACK/NACK) mapped to theinability by allocating a cyclic shift value with respect to a CPRBbased on CPRB indication information.

Technical objects of the present invention are not limited to thoseobjects described above; other technical objects not mentioned above canbe clearly understood from what are described below by those skilled inthe art to which the present invention belongs.

Technical Solution

To achieve the technical object, in a method for transmitting uplink(UL) data requiring low latency in a wireless communication systemaccording to the present invention, the method carried out by a mobileterminal comprises transmitting contention PUSCH resource block (CPRB)indication information used for identifying a particular terminal and/orparticular data to a base station; transmitting UL data to the basestation through CPRB resources of a contention based PUSCH (CP) zone;and receiving a hybrid automatic retransmit request (HARQ) response withrespect to the UL data from the base station through a physical hybridARQ indicator channel (PHICH), where the CP zone is a resource area fromwhich UL data can be transmitted without allocation of an UL grant and acyclic shift (CS) set up based on the CPRB indication information ismapped to the CPRB resource and the PHICH.

The CPRB indication information is a signal or a sequence transmittedthrough a physical uplink shared channel (PUSCH) or a physical uplinkcontrol channel (PUCCH).

The value of a cyclic shift ranges from 0 to <(the maximum value of theCPRB indication information value+1)/N>−1 for the same CPRB.

The PHICH is assigned for each terminal according to the cyclic shiftvalue.

The CPRB indication information and the UL data are transmitted from thesame subframe or through consecutive subframes.

In a method for receiving UL data requiring low latency in a wirelesscommunication system, the method carried out by a base station comprisesreceiving contention PUSCH resource block (CPRB) indication informationused for identifying a particular terminal and/or particular data fromat least two or more terminals; receiving uplink (UL) data through CPRBresource of a contention based PUSCH (CP) zone from the at least two ormore terminals; and transmitting a hybrid automatic retransmit request(HARQ) response with respect to the UL data through a physical hybridARQ indicator channel (PHICH) to the at least two or more terminals,where the CP zone is a resource area from which UL data can betransmitted without allocation of an UL grant and a cyclic shift (CS)set up based on the CPRB indication information is mapped to the CPRBresource and the PHICH.

A mobile terminal for transmitting uplink (UL) data in a wirelesscommunication system comprises a radio frequency (RF) unit fortransmitting and receiving a radio signal; and a processor, where theprocessor is controlled to transmit contention PUSCH resource block(CPRB) indication information used for identifying a particular terminaland/or particular data to a base station; to transmit uplink data to thebase station through CPRB resources of a contention based PUSCH (CP)zone; and to receive a hybrid automatic retransmit request (HARQ)response with respect to the UL data from the base station through aphysical hybrid ARQ indicator channel (PHICH); and where the CP zone isa resource area from which UL data can be transmitted without allocationof an UL grant and a cyclic shift (CS) set up based on the CPRBindication information is mapped to the CPRB resource and the PHICH.

Advantageous Effects

The present invention allocates a cyclic shift value with respect to aCPRB on the basis of CPRB indication information, thereby resolving acollision problem of UL data resources (e.g., demodulation-referencesignal (DMRS)) that can be caused by terminals' selection of the sameCPRB and increasing a probability of successfully transmitting andreceiving UL data.

The present invention allocates a cyclic shift value based on CPRBindication information, thereby resolving a collision problem duringtransmission and reception of an error correction response (HARQACK/NACK) with respect to UL data transmitted through the same CPRB.

The advantageous effects that can be obtained from application of thepresent invention are not limited to the aforementioned effects, butother advantageous effects not mentioned above will be clearlyunderstood from the descriptions below by those skilled in the art towhich the present invention belongs.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates one example of a network structure of evolveduniversal terrestrial radio access network (E-UTRAN) to which thepresent invention can be applied;

FIG. 2 illustrates a radio interface protocol structure defined betweena mobile terminal and an E-UTRAN in a wireless communication system towhich the present invention can be applied;

FIG. 3 illustrates physical channels used for the 3GPP LTE/LTE-A systemto which the present invention can be applied and a general signaltransmission method using the physical channels;

FIG. 4 illustrates a radio frame structure defined in the 3GPP LTE/LTE-Asystem to which the present invention can be applied;

FIG. 5 illustrates a resource grid with respect to one downlink slot ina wireless communication system to which the present invention can beapplied;

FIG. 6 illustrates a structure of a downlink subframe in a wirelesscommunication system to which the present invention can be applied;

FIG. 7 illustrates a structure of an uplink subframe in a wirelesscommunication system to which the present invention can be applied;

FIG. 8 illustrates a structure of DCI format 0 in a wirelesscommunication system to which the present invention can be applied;

FIG. 9 illustrates one example where PUCCH formats are mapped to thePUCCH region of an uplink physical resource block in a wirelesscommunication system to which the present invention can be applied;

FIG. 10 illustrates a structure of a CQI channel for the case of anormal CP in a wireless communication system to which the presentinvention can be applied;

FIG. 11 illustrates a structure of an ACK/NACK channel for the case of anormal CP in a wireless communication system to which the presentinvention can be applied;

FIG. 12 illustrates a method for multiplexing ACK/NACK and SR in awireless communication system to which the present invention can beapplied;

FIG. 13 illustrates an MAC PDU used by an MAC entity in a wirelesscommunication system to which the present invention can be applied;

FIGS. 14 and 15 illustrate a sub-header of an MAC PDU in a wirelesscommunication system to which the present invention can be applied;

FIG. 16 illustrates a format of an MAC control element for reporting abuffer state in a wireless communication system to which the presentinvention can be applied;

FIG. 17 illustrates one example of a component carrier and carrieraggregation in a wireless communication system to which the presentinvention can be applied;

FIG. 18 illustrates an uplink resource allocation process of a mobileterminal in a wireless communication system to which the presentinvention can be applied;

FIG. 19 illustrates latency in a C-plane required in the 3GPP LTE-Asystem to which the present invention can be applied;

FIG. 20 illustrates transition time of a synchronized terminal from adormant state to an active state required in the 3GPP LTE-A system towhich the present invention can be applied;

FIG. 21 illustrate one example of a random access procedure;

FIG. 22 illustrates another example of a structure of an uplinksubframe;

FIG. 23 illustrates a signal processing procedure for transmitting anuplink reference signal;

FIG. 24 illustrates a structure of a subframe for transmittingdemodulation reference signal;

FIG. 25 illustrates one example of setting a CP zone and a contentionPUSCH resource block;

FIG. 26 illustrates another example of a contention PUSCH resourceblock;

FIG. 27 illustrates one example of a method for transmitting informationrelated to a CP zone;

FIG. 28 illustrates one example of a method for using a CP zone in abuffer state report (BSR) procedure;

FIG. 29 illustrates various ways of setting a CP zone when a bufferstate report (BSR) procedure uses the CP zone;

FIG. 30 illustrates one example of a method for CPRB mapping in a bufferstate report (BSR) procedure;

FIG. 31 illustrates one example of collision occurred at the time of BSRtransmission due to occupation of the same CPRB;

FIG. 32 illustrates one example of a method for setting a DMRS cyclicshift of a CPRB according to the present invention;

FIG. 33 illustrates one example of a method for setting a DMRS cyclicshift value according to the present invention;

FIG. 34 illustrates another example of a method for setting a DMRScyclic shift value according to the present invention; and

FIG. 35 illustrates a block diagram of a wireless communication deviceto which the present invention can be applied.

MODE FOR INVENTION

In what follows, preferred embodiments according to the presentinvention will be described in detail with reference to appendeddrawings. The detailed descriptions given below with reference toappended drawings are intended only to provide illustrative embodimentsof the present invention and do not represent the only embodimentsthereof. The detailed descriptions of the present invention belowinclude specific details for the purpose of comprehensive understandingof the present invention. However, those skilled in the art may readilyunderstand that the present invention can be implemented without thosespecific details.

For some case, in order to avoid inadvertently making the technicalconcept of the present invention obscured, the structure and theapparatus well-known to the public can be omitted or illustrated in theform of a block diagram with respect to essential functions of thestructure and the apparatus.

A base station in this document is defined as a terminal node of anetwork which carries out communication directly with a terminal.Particular operations in this document described to be carried out by abase station may be carried out by an upper node of the base stationdepending on the situation. In other words, it is evident that in anetwork consisting of a plurality of network nodes including a basestation, various operations carried out for communication with terminalscan be carried out the base station or other network nodes other thanthe base station. The term of base station (BS) can be substituted forby those terms such as fixed station, Node B, evolved-NodeB (eNB), basetransceiver system (BTS), and access point (AP). Also, a terminal may bestationary or mobile and can be referred to by different terms such as aUser Equipment (UE), Mobile Station (MS), User Terminal (UT), MobileSubscriber Station (MSS), Subscriber Station (SS), Advanced MobileStation (AMS), Wireless Terminal (WT), Machine-Type Communication (MTC)device, Machine-to-Machine (M2M) device, and Device-to-Device (D2D)device.

In what follows, downlink transmission denotes communication from the BSto the UE, and uplink transmission denotes communication from the UE tothe BS. In the downlink transmission, a transmitter can be a part of theBS while a receiver can be a part of the UE. In the uplink transmission,a transmitter can be a part of the UE while a receiver can be a part ofthe base station.

Particular terms used in the descriptions below are introduced to helpunderstand the present invention and can be modified in various otherways as long as a modified use thereof does not depart from thetechnical principles and concept of the present invention.

Technologies described below can be used by various wireless accesssystems based on the scheme such as CDMA (code division multipleaccess), FDMA (frequency division multiple access), TDMA (time divisionmultiple access), OFDMA (orthogonal frequency division multiple access),SC-FDMA (single carrier frequency division multiple access), and NOMA(non-orthogonal multiple access). The CDMA scheme can be implemented bya radio technology such as universal terrestrial radio access (UTRA) andCDMA2000. The TDMA scheme can be implemented by a radio technology suchas global system for mobile communications (GSM), general packet radioservice (GPRS), and enhanced data rates for GSM evolution (EDGE). TheOFDMA scheme can be implemented by such as radio technology as definedby the IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, andevolved UTRA (E-UTRA). The UTRA is a part of standards specifying theuniversal mobile telecommunications system (UMTS). The 3^(rd) generationpartnership project (3GPP) long term evolution (LTE) is a part ofstandards of the evolved UMTS (E-UMTS) employing the E-UTRA, employingthe OFDMA scheme for downlink transmission and the SC-FDMA scheme foruplink transmission. The LTE-A (Advanced) is an enhancement of the 3GPPLTE standard.

The embodiments of this document can be supported by at least one of thestandard specifications for wireless access systems such as the IEEE802, 3GPP, and 3GPP2. In other words, the standard specifications can beused to support those steps or parts among the embodiments of thepresent invention not explicitly described in favor of clarifying thetechnical principles thereof. Also, for technical definitions of theterms used in this document, the standard documents should be consulted.

For the purpose of clarity, this document is described based on the 3GPPLTE/LTE-A standard; however, it should be understood that the presentinvention is not limited to the specific standard.

The Overall System

FIG. 1 illustrates one example of a network structure of the evolveduniversal terrestrial radio access network (E-UTRAN) to which thepresent invention can be applied.

The E-UTRAN system is an enhancement of the UTRAN system, and can bereferred to as the 3GPP LTE/LTE-A system. The E-UTRAN system includeseNBs which provide a control plane and a user plane to a UE, and theeNBs are connected to each other through X2 interface. The X2 user planeinterface (X2-U) is defined among the eNBs. The X2-U interface isintended to provide non-guaranteed delivery of a user plane's packetdata unit (PDU). The X2 control plane interface (X2-CP) is definedbetween two neighboring eNBs. The X2-CP performs the function of contextdelivery between eNBs, control of a user plane tunnel between a sourceeNB and a target eNB, delivery of handover-related messages, and uplinkload management. An eNB is connected to a UE through an air interfaceand connected to an evolved packet core (EPC) through the S1 interface.The S1 user plane interface (S1-U) is defined between an eNB and aserving gateway (S-GW). The S1 control plane interface (S1-MME) isdefined between an eNB and a mobility management entity (MME). The S1interface performs an evolved packet system (EPS) bearer servicemanagement function, a non-access stratum (NAS) signaling transportfunction, network sharing, an MME load balancing function, and so on.The S1 interface supports many-to-many relation between an eNB and anMME/S-GW.

FIG. 2 illustrates a radio interface protocol structure defined betweena UE and an E-UTRAN in a wireless communication system to which thepresent invention can be applied. FIG. 2(a) illustrates a radio protocolstructure of a control plane, and FIG. 2(b) illustrates a radio protocolstructure of a user plane.

With reference to FIG. 2, layers of a radio interface protocol betweenthe UE and the E-UTRAN can be classified into a first layer (L1), asecond layer (L2), and a third layer (L3) based on the lower threelayers of the open system interconnection (OSI) model that is well-knownin the communication system technology field. The radio interfaceprotocol between the UE and the E-UTRAN is divided horizontally into aphysical layer, a data link layer, and a network layer; and dividedvertically into a user plane which is a protocol stack for datainformation transmission and a control plane which is a protocol stackfor transmission of a control signal.

The control plane refers to a path along which control messages for theUE and the network to manage calls are transmitted. The user planerefers to a path along which data created in the application layer, forexample, voice data or Internet packet data are transmitted. In whatfollows, the control plane and the user plane of the radio protocol willbe described. The physical (PHY) layer belonging to the first layerprovides an information transfer service to an upper layer by using aphysical channel. The PHY layer is connected to the medium accesscontrol (MAC) layer belonging to the upper layer through a transportchannel, and data are transferred between the MAC layer and the PHYlayer through the transport channel. The transport channel is classifiedaccording to how and with what characteristics data are transferredthrough a radio interface. And a physical channel is employed totransfer data between disparate physical layers and between a physicallayer of a transmitter end and a physical layer of a receiver end. Thephysical layer is modulated by OFDM scheme and uses time and frequencyas radio resources.

There are a few physical control channels used in the physical layer. Aphysical downlink control channel (PDCCCH) informs the UE of a pagingchannel (PCH), resource allocation of a downlink shard channel (DL-SCH),and hybrid automatic repeat request (HARQ) information related to anuplink shared channel (UL-SCH). Also, the PDCCH can carry an uplinkgrant which informs the UE of resource allocation for uplinktransmission. A physical control format indicator channel (PDFICH)informs the UE of the number of OFDM symbols used for the PDCCHs and istransmitted for each subframe. A physical HARQ indicator channel (PHICH)carries a HARQ acknowledge (ACK)/non-acknowledge (NACK) signal inresponse to the uplink transmission. A physical uplink control channel(PUCCH) carries requests scheduling of the HARQ ACK/NACK signal fordownlink transmission and carries uplink control information such as achannel quality indicator (CQI). A physical uplink shared channel(PUSCH) carries an UL-SCH.

The MAC layer of the second layer (L2) provides a service to its upperlayer, radio link control (RLC) layer, through a logical channelFunctions of the MAC layer includes mapping between a logical channeland a transport channel; and multiplexing/demultiplexing of transportblocks provided to a physical channel on a transport channel of a MACservice data unit (SDU) belonging to the logical channel.

The RLC layer of the second layer (L2) supports reliable transmission ofdata. Functions of the RLC layer include concatenation, segmentation,and reassembly of the RLC SDU. To ensure various levels of quality ofservice (QoS) that a radio bearer (RB) requests, the RLC layer providesthree operating modes: transparent mode (TM), unacknowledged mode (UM),and acknowledge mode (AM). The AM RLC provides error correction throughan automatic repeat request (ARQ). Meanwhile, in case the MAC layercarries the RLC function, the RLC layer can be included as a functionalblock of the MAC layer.

A packet data convergence protocol (PDCP) layer of the second layer (L2)carries functions of transfer of user data in the user plane, headercompression, and ciphering. The header compression refers to thefunction of reducing the size of the IP packet header which carriesrelatively large and unnecessary control information so that Internetprotocol (IP) packets such as the Internet protocol version 4 (IPv4) orthe Internet protocol version 6 (IPv6) can be transmitted efficientlythrough a radio interface with narrow bandwidth. Functions of the PDCPlayer in the control plane include transfer of plane data andciphering/integrity protection.

The radio resource control (RRC) layer located in the lowest part of thethird layer (L3) is defined only in the control plane. The RRC layercontrols radio resources between the UE and a network. To this end, theUE and the network exchanges RRC messages through the RRC layer. The RRClayer controls a logical channel, a transport channel, and a physicalchannel related to configuration, re-configuration, and release of radiobearers. A radio bearer refers to a logical path that the second layer(L2) provides for data transmission between the UE and the network.Configuring a radio bearer indicates that a radio protocol layer andchannel characteristics are defined for providing a particular serviceand specific parameters and an operating method thereof are set up. Aradio bearer is again divided into a signaling RB (SRB) and a data RB(DRB). The SRB is used as a path for transmitting RRC messages in thecontrol plan, and the DRB is used as a path for transmitting user datain the user plane.

The non-access stratum (NAS) layer located in the upper hierarchy of theRRC layer performs the function of session management, mobilitymanagement, and so on.

A cell constituting an eNB has bandwidth chosen from among 1.25, 2.5, 5,10, 2 MHz and provides a downlink or an uplink transmission service toUEs. Bandwidth configuration can be carried out so that different cellshave bandwidth different from each other.

Downlink transport channels for transporting data from a network to a UEinclude a broadcast channel (BCH) which transmits system information, aPCH which transmits a paging message, a DL-SCH which transmits usertraffic or a control message. Downlink multicast or broadcast servicetraffic or a control message may be transmitted through the DL-SCH orthrough a separate multicast channel (MCH). Meanwhile, uplink transportchannels for transporting data from the UE to the network include arandom access channel (RACH) which transmits the initial control messageand an uplink shared channel which transmits user traffic or a controlmessage.

A logical channel lies in the upper hierarchy of a transport channel andis mapped to the transport channel. A logical channel is divided into acontrol channel for transmission of control area information and atraffic channel for transmission of user area information. Logicalchannels include a broadcast control channel (BCCH), a paging controlchannel (PCCH), a common control channel (CCCH), a dedicated controlchannel (DCCH), a multicast control channel (MCCH), a dedicated trafficchannel (DTCH), and a multicast traffic channel (MTCH).

To manage a UE and mobility of the UE in the NAS layer located in thecontrol plane, an EPS mobility management (EMM) registered state and anEMM-deregistered state can be defined. The EMM registered state and theEMM de-registered state can be applied to the UE and the MME. As in thecase when the UE is powered on for the first time, the UE at its initialstage is in the EMM-deregistered state and carries out a process ofregistering for a network through an initial attach procedure to connectto the corresponding network. If the connection procedure is carried outsuccessfully, the UE and the MME then make a transition to theEMM-registered state.

Also, to manage signaling connection between the UE and the network, anEPS connection management (ECM) connected state and an ECM-IDLE statecan be defined. The ECM-CONNECTED state and the ECM-IDLE state can alsobe applied to the UE and the MME. The ECM connection includes an RRCconnection established between the UE and an eNB and an S1 signalingconnection established between the eNB and the MME. The RRC stateindicates whether the RRC layer of the UE and the RRC layer of the eNBare connected logically to each other. In other words, if the RRC layerof the UE is connected to the RRC layer of the eNB, the UE stays in anRRC_CONNECTED state. If the RRC layer of the UE and the RRC layer of theeNB are not connected to each other, the UE stays in an RRC_IDLE state.

A network is capable of perceiving existence of a UE in theECM-CONNECTED state at the cell level and controlling the UE in aneffective manner. On the other hand, the network is unable to perceivethe existence of a UE in the ECM-IDLE state, and a core network (CN)manages the UE on the basis of a tracking area which is a regional unitlarger than the cell. If the UE is in the ECM-IDLE state, the UE carriesout discontinuous reception (DRX) that the NAS configures by using theID assigned uniquely in the tracking area. In other words, the UE canreceive broadcast data of system information and paging information bymonitoring a paging signal in a particular paging opportunity at eachUE-particular paging DRX cycle. When the UE is in the ECM-IDLE state,the network does not hold context information of the UE. Therefore, theUE in the ECM-IDLE state can carry out a mobility-related procedurebased on the UE such as cell selection or cell reselection withouthaving to take an order of the network. In case the position of the UEin the ECM-IDLE state changes from the position known to the network,the UE can inform the network about its position through a tracking areaupdate (TAU) procedure. On the other hand, if the UE is in theECM-CONNECTED state, mobility of the UE is managed by the command of thenetwork. While the UE is in the ECM-CONNECTED state, the network isinformed of the cell to which the UE belongs to. Therefore, the networktransmits and receives data to and from the UE, controls mobility suchas the UE's handover, and carries out cell measurement of neighboringcells.

As described above, in order for the UE to receive a conventional mobilecommunication service such as voice or data communication, the UE needsto make a transition to the ECM-CONNECTED state. When the UE is poweredon for the first time, the UE at its initial stage stays in the ECM-IDLEstate similarly as done for the EMM state; if the UE is registeredsuccessfully to the corresponding network through the initial attachprocedure, the UE and the MME make a transition to the ECM-CONNECTEDstate. Also, if the UE is registered in the network but radio resourcesare not assigned as traffic is deactivated, the UE stays in the ECM-IDLEstate; if new uplink or downlink traffic is generated for thecorresponding UE, the UE and the MME make a transition to theECM-CONNECTED state through a service request procedure.

FIG. 3 illustrates physical channels used for the 3GPP LTE/LTE-A systemto which the present invention can be applied and a general signaltransmission method using the physical channels.

A UE, which may have been powered on again from the power-off state ormay have newly entered a cell, carries out the initial cell search tasksuch as synchronizing itself with an eNB in the S301 step. To thispurpose, the UE synchronizes with the eNB by receiving a primarysynchronization channel (P-SCH) and a secondary synchronization channel(S-SCH) from the eNB and obtains information such as a cell ID(identifier).

Afterwards, the UE receives a physical broadcast channel (PBCH) signalfrom the eNB and obtains broadcast signal within the eNB. Meanwhile, theUE receives a downlink reference signal (DL RS) in the initial cellsearch step to check the downlink channel status.

The UE which has finished the initial cell search receives a PDSCHaccording to the PDCCH and PDCCH information in the S302 step to obtainmore specific system information.

Next, the UE may carry out a random access procedure such as the stepsof S303 to S306 to complete a connection process to the eNB. To thispurpose, the UE transmits a preamble S303 through a physical randomaccess channel (PRACH) and receives a response message in response tothe preamble through a PDSCH corresponding to the PRACH S304. In thecase of contention-based random access, the UE may carry out acontention resolution procedure including transmission of an additionalPRACH signal S305 and reception of a PDCCH signal and the PDSCH signalcorresponding to the PDCCH signal S306.

Afterwards, the UE which has carried out the procedure above may carryout reception S307 of the PDCCH signal and/or PDSCH signal andtransmission S308 of a PUSCH signal and/or a PUCCH signal as aconventional uplink/downlink signal transmission procedure.

The control information that the UE transmits to the eNB is calledcollectively uplink control information (UCI). The UCI includesHARQ-ACK/NACK, a scheduling request (SR), a channel quality indicator(CQI), a precoding matrix indicator (PMI), and rank indication (RI)information.

In the LTE/LTE-A system, the UCI is transmitted periodically through thePUCCH; the UCI can be transmitted through the PUSCH if controlinformation and traffic data have to be transmitted at the same time.Also, the UCI can be transmitted non-periodically through the PUSCHaccording to a request or a command from the network.

FIG. 4 illustrates a radio frame structure defined in the 3GPP LTE/LTE-Asystem to which the present invention can be applied.

In the cellular OFDM wireless packet communication system, transmissionof uplink/downlink data packets is carried out in units of subframes,and one subframe is defined as a predetermined time period including aplurality of OFDM symbols. The 3GPP LTE/LTE-A standard supports a type 1radio frame structure that can be applied to frequency division duplex(FDD) scheme and a type 2 radio frame structure that can be applied totime division duplex (TDD) scheme. In the FDD mode, uplink transmissionand downlink transmission are carried out separately in the respectivefrequency bands. On the other hand, for the TDD mode, uplink anddownlink transmission are carried out separately in the time domain butoccupy the same frequency band. Channel responses in the TDD mode are infact reciprocal. This implies that a downlink channel response isvirtually the same as the corresponding uplink channel response in thefrequency domain. Therefore, it can be regarded as an advantage for awireless communication system operating in the TDD mode that a downlinkchannel response can be obtained from an uplink channel response. Sincethe whole frequency domain is so utilized in the TDD mode that uplinkand downlink transmission are performed in time division fashion,downlink transmission by an eNB and uplink transmission by a UE cannotbe performed simultaneously. In a TDD system where uplink and downlinktransmission are managed in units of subframes, uplink and downlinktransmission are carried out separately in the respective subframes.

FIG. 4(a) illustrates a structure of a type 1 radio frame. A downlinkradio frame consists of 10 subframes, and each subframe consists of twoslots in the time domain. The time period needed to transmit onesubframe is called a Transmission Time Interval (TTI). For example,length of each subframe can amount to 1 ms, and length of each slot canbe 0.5 ms. Each slot includes a plurality of orthogonal frequencydivision multiplexing (OFDM) symbols in the time domain, and includes aplurality of resource blocks (RBs) in the frequency domain. The 3GPPLTE/LTE-A system uses the OFDMA method for downlink transmission;therefore, the OFDM symbol is intended to represent one symbol period.One OFDM symbol may be regarded to correspond to one SC-FDMA symbol or asymbol period. The resource block as a unit for allocating resourcesincludes a plurality of consecutive subcarriers within one slot.

The number of OFDM symbols included within one slot can be variedaccording to the configuration of a cyclic prefix. The CP has anextended CP and a normal CP. For example, in case the OFDM symbolconsists of normal CPs, the number of OFDM symbols included within oneslot can be 7. In case the OFDM symbol consists of extended CPs, thenumber of OFDM symbols included within one slot becomes smaller thanthat for the normal CP case since the length of a single OFDM isincreased. In the case of extended CP, for example, the number of OFDMsymbols included within one slot can be 6. In case a channel conditionis unstable as observed when the UE moves with a high speed, theextended CP can be used to further reduce inter-symbol interference.

Since each slot consists of 7 OFDM symbols when a normal CP is used, onesubframe includes 14 OFDM symbols. At this time, the first maximum 3OFDM symbols of each subframe are allocated to the physical downlinkcontrol channel (PDCCH) and the remaining OFDM symbols are allocated tothe physical downlink shared channel (PDSCH).

FIG. 4(b) illustrates a type 2 radio frame. The type 2 radio frameconsists of two half frames, and each half frame consists of 5subframes, and each subframe consists of two slots. Among the 5subframes, a special subframe consists of a downlink pilot time slot(DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). TheDwPTS is used for the UE to carry out the initial cell search,synchronization, and channel estimation. The UpPTS is used for the eNBto carry out channel estimation and uplink transmission synchronizationwith the UE. The GP is a period intended for removing interferencegenerated during uplink transmission due to multi-path delay of adownlink signal between uplink and downlink transmission.

The structure of a radio frame described above is just an example, andthe number of subframes included within one radio frame, the number ofslots included within one subframe, and the number of symbols includedwithin one slot can be varied in many ways.

FIG. 5 illustrates a resource grid with respect to one downlink slot ina wireless communication system to which the present invention can beapplied.

With reference to FIG. 5, one downlink slot includes a plurality of OFDMsymbols in the time domain. Each downlink slot includes 7 OFDM symbols,and each resource block includes 12 subcarriers in the frequency domain.However, the present invention is not limited to the illustrativeconfiguration.

Each element of resource grids is called a resource element, and aresource block includes 12×7 resource elements. Each resource element inthe resource grids can be identified by an index pair (k, l) within aslot. Here, k (k=0, . . . , N_(RB)×12−1) stands for a subcarrier indexin the frequency domain while l (l=0, . . . , 6) an OFDM symbol index inthe time domain. The number N_(RB) of resource blocks included in adownlink slot is dependent on downlink transmission bandwidth. Thestructure of an uplink slot can be the same as that of the downlinkslot.

FIG. 6 illustrates a structure of a downlink subframe in a wirelesscommunication system to which the present invention can be applied.

With reference to FIG. 6, in the first slot within a subframe, the firstmaximum three OFDM symbols make up a control region to which controlchannels are allocated, and the remaining OFDM symbols form a dataregion to which a PDSCH is allocated. The 3GPP LTE/LTE-A standarddefines PCFICH, PDCCH, and PHICH as downlink control channels.

The PCFICH is transmitted from the first OFDM symbol of a subframe andcarries information about the number (namely, size of the controlregion) of OFDM symbols used for transmission of control channels withina subframe. The PHICH is a response channel with respect to an uplinkand carries a ACK/NACK signal with respect to HARQ. The controlinformation transmitted through the PDCCH is called downlink controlinformation (DCI). The DCI includes uplink resource allocationinformation, downlink resource allocation information, or uplinktransmission (Tx) power control commands for an arbitrary UE group.

An eNB determines the PDCCH format according to Downlink ControlInformation (DCI) to be sent to a UE and adds a Cyclic Redundancy Check(CRC) to the control information. The CRC is masked with a uniqueidentifier depending on an owner of the PDCCH or intended use of thePDCCH, which is called a Radio Network Temporary Identifier (RNTI). Inthe case of a PDCCH intended for a particular UE, a unique identifierfor the UE, for example, Cell-RNTI (C-RNTI) can be masked with the CRC.Similarly, the CRC can be masked with a paging identifier, for example,Paging-RNTI (P-RNTI) in the case of a PDCCH intended for a pagingmessage. The CRC can be masked with a system information identifier, forexample, System Information-RNTI (SI-RNTI) in the case of a PDCCHintended for system information block. The CRC can be masked with aRandom Access-RNTI (RA-RNTI) to designate a random access response inresponse to transmission of a random access preamble of the UE.

FIG. 7 illustrates a structure of an uplink subframe in a wirelesscommunication system to which the present invention can be applied.

With reference to FIG. 7, an uplink subframe is divided into a controlregion and a data region in the frequency domain. A PUCCH which carriesuplink control information is allocated to the control region. A PUSCHwhich carries data is allocated to the data region. If an upper layercommands, the UE can support the PUSCH and the PUCCH at the same time. Aresource block pair is allocated within a subframe for the PUCCH of eachUE. The resource blocks belonging to a resource block pair allocated tothe PUCCH occupy different subcarriers at each of two slots based on aslot boundary. In this case, the resource block pair allocated to thePUCCH is said to perform frequency hopping at slot boundaries.

Physical Downlink Control Channel (PDCCH)

The control information transmitted through a PDCCH is called downlinkcontrol indicator (DCI). The size and use of the control informationtransmitted through the PDCCH vary according to the DCI format, and thesize can still be changed according to a coding rate.

Table 1 shows the DCI according to the DCI format.

TABLE 1 DCI format Objectives 0 Scheduling of PUSCH 1 Scheduling of onePDSCH codeword 1A Compact scheduling of one PDSCH codeword 1BClosed-loop single-rank transmission 1C Paging, RACH response anddynamic BCCH 1D MU-MIMO 2 Scheduling of rank-adapted closed-loop spatialmultiplexing mode 2A Scheduling of rank-adapted open-loop spatialmultiplexing mode 3 TPC commands for PUCCH and PUSCH with 2 bit poweradjustments 3A TPC commands for PUCCH and PUSCH with single bit poweradjustments 4 the scheduling of PUSCH in one UL cell with multi-antennaport transmission mode

With reference to Table 1, each value of the DCI format indicates thefollowing objective: format 0 for scheduling of PUSCH, format 1 forscheduling of one PDSCH codeword, format 1A for compact scheduling ofone PDSCH codeword, format 1C for very compact scheduling of DL-SCH,format 2 for PDSCH scheduling in a closed-loop spatial multiplexingmode, format 2A for PDSCH scheduling in an open loop spatialmultiplexing mode, format 3 and 3A for transmission of transmissionpower control (TPC) command for an uplink channel, and format 4 forPUSCH scheduling within one uplink cell in a multi-antenna porttransmission mode.

The DCI format 1A can be used for PDSCH scheduling no matter whattransmission mode is applied.

The DCI format can be applied separately for each UE, and PDCCHs formultiple UEs can be multiplexed within one subframe. A PDCCH is formedby aggregation of one or a few consecutive control channel elements(CCEs). A CCE is a logical allocation unit used for providing a PDCCHwith a coding rate according to the state of a radio channel. One REGcomprises four REs, and one CCE comprises nine REGs. To form one PDCCH,{1, 2, 4, 8} CCEs can be used, and each element of the set {1, 2, 4, 8}is called a CCE aggregation level. The number of CCEs used fortransmission of a particular PDCCCH is determined by the eNB accordingto the channel condition. The PDCCH established according to each UE ismapped being interleaved to the control channel region of each subframeaccording to a CCE-to-RE mapping rule. The position of the PDCCH can bevaried according to the number of OFDM symbols for a control channel ofeach subframe, the number of PHICH groups, transmission antenna, andfrequency transition.

As described above, channel coding is applied independently to the PDCCHof each of the multiplexed UEs, and cyclic redundancy check (CRC) isapplied. The CRC is masked with a unique identifier (ID) of each UE sothat the UE can receive its PDCCH. However, the eNB does not inform theUE about the position of the corresponding PDCCH in the control regionallocated within a subframe. Since the UE is unable to get informationabout from which position and at which CCE aggregation level or in whichDCI format the UE's PDCCH is transmitted to receive a control channeltransmitted from the eNB, the UE searches for its PDCCH by monitoring aset of PDCCH candidates within the subframe. The above operation iscalled blind decoding (BD). Blind decoding can be also called blinddetection or blind search. The blind decoding refers to the method withwhich the UE demasks the UE ID in the CRC section and checks any CRCerror to determine whether the corresponding PDCCH is the UE's controlchannel.

In what follows, described will be the information transmitted throughthe DCI format 0.

FIG. 8 illustrates a structure of DCI format 0 in a wirelesscommunication system to which the present invention can be applied.

The DCI format 0 is used for scheduling a PUSCH in an uplink cell.

Table 2 shows the information transmitted through the DCI format 0.

TABLE 2 Format 0 (Release 8) Format 0 (Release 10) Carrier Indicator(CIF) Flag for format 0/format 1A Flag for format 0/format 1Adifferentiation differentiation Hopping flag (FH) Hopping flag (FH)Resource block assignment (RIV) Resource block assignment (RIV) MCS andRV MCS and RV NDI (New Data Indicator) NDI (New Data Indicator) TPC forPUSCH TPC for PUSCH Cyclic shift for DM RS Cyclic shift for DM RS ULindex (TDD only) UL index (TDD only) Downlink Assignment Index (DAI)Downlink Assignment Index (DAI) CSI request (1 bit) CSI request (1 or 2bits: 2 bit is for multi carrier) SRS request Resource allocation type(RAT)

With reference to FIG. 8 and Table 2, the information transmittedthrough the DCI format 0 is as follows.

1) Carrier indicator—consists of 0 or 3 bits.

2) Flag for identifying the DCI format 0 and format 1A—consists of 1bit, where 0 indicates the DCI format 0 and 1 indicates the DCI format1A.

3) Frequency hopping flag—consists of 1 bit. This field can be used toallocate the most significant bit (MSB) of the corresponding resourceallocation for multi-cluster allocation depending on the needs.

Resource block assignment and hopping resource allocation—consists of┌log₂ (N_(RB) ^(DL)(N_(RB) ^(DL)+1)/2)┐ bits.

In the case of PUSCH hopping for single-cluster allocation, NUL_hop MSBsare used to obtain the value of ñ_(PRB)(i). The (┌log₂ (N_(RB)^(UL)(N_(RB) ^(UL)+1)/2)┐−N_(UL) _(_) _(hop)) bit provides resourceallocation of the first slot within an uplink subframe. Also, in casethere is no PUSCH hopping for single-cluster allocation, the (┌log₂(N_(RB) ^(UL)(N_(RB) ^(UL)+1)/2)┐) bit provides resource allocationwithin the uplink subframe. Also, in case there is no PUSCH hopping formulti-cluster allocation, resource allocation information is obtainedfrom concatenation of a frequency hopping flag, resource blockallocation, and hopping resource allocation field; and the

$\left\lceil {\log_{2}\left( \begin{pmatrix}\left\lceil {{N_{RB}^{UL}\text{/}P} + 1} \right\rceil \\4\end{pmatrix} \right)} \right\rceil$

bit provides resource allocation within the uplink subframe. At thistime, the P value is determined by the number of downlink resourceblocks.

5) Modulation and coding scheme—consists of 5 bits.

6) New data indicator—consists of 1 bit.

7) Transmit power control command for PUSCH—consists of 2 bits.

8) Index of cyclic shift for demodulation reference signal (DMRS) andorthogonal cover/orthogonal cover code (OC/OCC)—consists of 3 bits.

9) Uplink index—consists of 2 bits. This field is defined only for theTDD operation according to uplink-downlink configuration 0.

10) Downlink assignment index (DAI)—consists of 2 bits. This field isdefined only for the TDD operation according to uplink-downlinkconfiguration 1 to 6.

11) Channel state information (CSI) request—consists of 1 bit or 2 bits.At this time, a two-bit field is applied only when the corresponding DCIis mapped to the UE, for which one or more downlink cells areconfigured, by Cell-RNTI (C-RNTI) in a UE-specific manner.

12) Sounding reference signal (SRS) request—consists of 0 or 1 bit. Atthis time, this field is defined only when a scheduling PUSCH is mappedby the C-RNTI in a UE-specific manner.

13) Resource allocation type—consists of 1 bit.

In case the number of information bits within the DCI format 0 issmaller than the payload size of the DCI format 1A (including a paddingbit), 0 is added to the DCI format 0 so that the number of informationbits is equal to the payload size of the DCI format 1A.

Physical Uplink Control Channel (PUCCH)

A PUCCH carries various types of uplink control information (UCI) asfollows according to the format.

-   -   Scheduling request (SR): information used for requesting uplink        UL-SCH resources. An on-off keying method is used for        transmission of an SR.    -   HARQ ACK/NACK: a response signal with respect to downlink data        packet on a PDSCH. HARQ ACK/NACK indicates whether a downlink        data packet has been successfully received. In response to a        single downlink codeword, ACK/NACK 1 bit is transmitted, and in        response to two downlink codewords, ACK/NACK 2 bits are        transmitted.    -   Channel state information (CSI): feedback information about a        downlink channel CSI includes at least one of channel quality        indicator (CQI), rank indicator (RI), precoding matrix indicator        (PMI), and precoding type indicator (PTI). In what follows, for        the convenience of description, CQI is used to represent the        various terms above.

A PUCCH can be modulated by BPSK (Binary Phase Shift Keying) and QPSK(Quadrature Phase Shift Keying) methods. Control information of aplurality of UEs can be transmitted through the PUCCH; in case codedivision multiplexing (CDM) is carried out to identify individualsignals of the UEs, a constant amplitude zero auto correlation (CAZAC)sequence of length 12 is usually employed. Since a CAZAC sequence tendsto keep a constant amplitude in the time domain and the frequencydomain, the CAZAC sequence is useful for the UE to increase coverage byreducing the UE's peak-to-average power ratio (PAPR) or cubic metric(CM). Also, the ACK/NACK information about downlink data transmittedthrough the PUCCH is covered by an orthogonal sequence or an orthogonalcover (OC).

Also, control information transmitted on the PUCCH can be identified bya cyclically shifted sequence which has a different cyclic shift valuefrom the others. A cyclically shifted sequence can be created bycyclically shifting a base sequence by as many as a predetermined cyclicshift amount. The amount of cyclic shift is specified by a CS index. Thenumber of cyclic shifts available can be varied according to a delayspread of the corresponding channel Various types of sequences can beused as a base sequence, and the aforementioned CAZAC sequence is one ofthe examples.

Also, the amount of control information that the UE can transmit from asubframe can be determined according to the number of SC-FDMA symbolsavailable for transmission of the control information (which indicatesSC-FDMA symbols excluding the SC-FDMA symbol used for transmission of areference signal (RS) for coherent detection of the PUCCH, but in thecase of a subframe for which a sounding reference signal (SRS) is setup, the last SC-FDMA symbol of the subframe is also excluded).

A PUCCH is defined by 7 different formats according to controlinformation transmitted, a modulation method used, the amount of controlinformation, and so on. Properties of the uplink control information(UCI) transmitted according to each PUCCH format can be summarized asshown in Table 3.

TABLE 3 PUCCH Format Uplink Control Information(UCI) Format 1 SchedulingRequest(SR)(unmodulated waveform) Format 1a 1-bit HARQ ACK/NACKwith/without SR Format 1b 2-bit HARQ ACK/NACK with/without SR Format 2CQI (20 coded bits) Format 2 CQI and 1- or 2-bit HARQ ACK/NACK (20 bits)for extended CP only Format 2a CQI and 1-bit HARQ ACK/NACK (20 + 1 codedbits) Format 2b CQI and 2-bit HARQ ACK/NACK (20 + 2 coded bits) Format 3HARQ ACK/NACK, SR, CSI (48 coded bits)

With reference to Table 3, the PUCCH format 1 is used for exclusivetransmission of a scheduling request (SR). In the case of exclusivetransmission of an SR, an unmodulated waveform is applied.

The PUCCH format 1a or 1b is used for transmission of HARQ ACK/NACK(Acknowledgement/Non-Acknowledgement). In case the HARQ ACK/NACK istransmitted exclusively in an arbitrary subframe, the PUCCH format 1a or1b can be used. HARQ ACK/NACK and SR may be transmitted from the samesubframe by using the PUCCH format 1a or 1b.

The PUCCH format 2 is used for transmission of CQI, and the PUCCH format2a or 2b is used for transmission of CQI and HARQ ACK/NACK. In the caseof an extended CP, the PUCCH format 2 may be used for transmission ofCQI and HARQ ACK/NACK.

The PUCCH format 3 is used to carry 48 bit encoded UCI. The PUCCH format3 can carry HARQ ACK/NACK with respect to a plurality of serving cells,SR (in the case it exists), and CSI report about each serving cell.

FIG. 9 illustrates one example where PUCCH formats are mapped to thePUCCH region of an uplink physical resource block in a wirelesscommunication system to which the present invention can be applied.

A PUCCH with respect to one UE is allocated to a resource block pair (RBpair) in a subframe. Resource blocks belonging to a resource block pairoccupy different subcarriers in each of the first and the second slot.The frequency band occupied by a resource block belonging to theresource block pair allocated to a PUCCH is changed with respect to aslot boundary. In this case, the resource block pair allocated to thePUCCH is said to perform frequency hopping at slot boundaries. The UE,by transmitting uplink control information through subcarriers differentwith time, frequency diversity gain can be obtained.

In FIG. 9, N_(RB) ^(UL) represents the number of resource blocks inuplink transmission, and 0, 1, . . . , N_(RB) ^(UL)−1 denotes the numberassigned to a physical resource block. By default, the PUCCH is mappedto both ends of an uplink frequency block. As shown in FIG. 9, the PUCCHformat 2/2a/2b is mapped to the PUCCH region designated as m=0, 1, whichcan be interpreted that the PUCCH format 2/2a/2b is mapped to resourceblocks located at band edges. Also, the PUCCH format 2/2a/2b and thePUCCH format 1/1a/1b can be mapped being mixed together to the PUCCHregion designated as m=2. Next, the PUCCH format 1/1a/1b can be mappedto the PUCCH region designated as m=3, 4, 5. The number N_(RB) ⁽²⁾ ofPUCCH RBs made available by the PUCCH format 2/2a/2b can be notified tothe UEs within a cell through broadcasting signaling.

Table 4 shows a modulation method according to a PUCCH format and thenumber of bits per subframe. In Table 4, the PUCCH format 2a and 2bcorrespond to the case of a normal cyclic shift.

TABLE 4 PUCCH Modulation Number of bits per format scheme subframe,M_(bit) 1 N/A N/A 1a BPSK 1 1b QPSK 2 2 QPSK 20 2a QPSK + BPSK 21 2bQPSK + QPSK 22 3 QPSK 48

Table 5 shows the number of symbols of a PUCCH demodulation referencesignal per slot according to the PUCCH format.

TABLE 5 PUCCH format Normal cyclic prefix Extended cyclic prefix 1, 1a,1b 3 2 2, 3 2 1 2a, 2b 2 N/A

Table 6 shows SC-FDMA symbol position of a PUCCH demodulation referencesignal according to the PUCCH format. In Table 6, l represents a symbolindex.

TABLE 6 Set of values for l PUCCH format Normal cyclic prefix Extendedcyclic prefix 1, 1a, 1b 2, 3, 4 2, 3 2, 3 1, 5 3 2a, 2b 1, 5 N/A

In what follows, the PUCCH format 2/2a/2b will be described.

The PUCCH format 2/2a/2b is used as CQI feedback (or ACK/NACKtransmission along with CQI feedback) with respect to downlinktransmission. In order for the CQI and ACK/NACK signal to be transmittedtogether, the ACK/NACK signal may be transmitted being embedded in theCQI RS (in the case of a normal CP) or transmitted after the CQI andACK/NACK signal are jointly coded (in the case of an extended CP).

FIG. 10 illustrates a structure of a CQI channel for the case of anormal CP in a wireless communication system to which the presentinvention can be applied.

Among SC-FDMA symbols 0 to 6 in one slot, SC-FDMA symbol 1 and 5 (thesecond and the sixth symbol) are used for transmission of a demodulationreference signal (DMRS), and the remaining SC-FDMA symbols are used totransmit CQI information. Meanwhile, in the case of an extended CP, oneSC-FDMA symbol (SC-FDMA symbol 3) is used for DMRS transmission.

The PUCCH format 2/2a/2b supports modulation based on a CAZAC sequence,and a QPSK-modulated symbol is multiplied with a CAZAC sequence oflength 12. The cyclic shift of the sequence is changed between a symboland a slot. Orthogonal covering is used for a DMRS.

Among 7 SC-FDMA symbols included in one slot, two SC-FDMA spaced apartfrom each other by three SC-FDMA symbols carries the DMRS, and theremaining 5 SC-FDMA symbols carry CQI information. The scheme of usingtwo reference signals in one slot is intended to support high-speed UEs.Also, each UE is identified on the basis of a cyclic shift sequence. TheCQI information symbols are transmitted being modulated with the entireSC-FDMA symbols, and each SC-FDMA symbol comprises one sequence. Inother words, each UE modulates the CQI and transmits the modulated CQIto each sequence.

The number of symbols that can be transmitted to one TTI is 10, andmodulation of CQI information is predetermined to use QPSK modulation.The first 5 symbols are transmitted from the first slot, and theremaining 5 symbols are transmitted from the second slot. In case QPSKmapping is used with respect to the SC-FDMA symbol, CQI value of twobits can be dealt with; therefore, each slot can carry CQI value of 10bits. Accordingly, a maximum of 20 bits can be used for each subframe tocarry the CQI value. In order to spread the CQI information in thefrequency domain, frequency domain spreading code is used.

For frequency domain spreading code, a CAZAC sequence of length 12 (forexample, zc sequence) can be used. Each control channel can beidentified by applying the CAZAC sequence with a different cyclic shiftvalue. Inverse fast fourier transform (IFFT) is carried out forfrequency domain spread CQI information.

Twelve different UEs can be orthogonally multiplexed on the same PUCCHRB by cyclic shift having 12 equivalent intervals. In the case of normalCP, the DMRS sequence on the SC-FDMA symbol 1 and 5 (in the case ofextended CP, on the SC-FDMA symbol 3) is similar to the CQI signalsequence in the frequency domain, but the same modulation as done forthe CQI information is not applied.

A UE can be configured semi-statically by upper layer signaling toreport different CQI, PMI, and RI types periodically on the PUCCHresources designated by the PUCCH resource index (n_(PUCCH)^((1,{tilde over (p)})), n_(PUCCH) ^((2,{tilde over (p)})), n_(PUCCH)^((3,{tilde over (p)})),). At this time, the PUCCH resource index(n_(PUCCH) ^((2,{tilde over (p)}))) corresponds to the informationindicating the PUCCH region used for PUCCH format 2/2a/2b transmissionand a cyclic shift (CS) value to be used.

Table 7 shows an orthogonal sequence (OC) [w ^(({tilde over (p)}))(0) .. . w ^(({tilde over (p)}))(N_(RS) ^(PUCCH)−1] for an RS defined by thePUCCH format 2/2a/2b/3.

TABLE 7 Normal cyclic prefix Extended cyclic prefix [1 1] [1]

Next, the PUCCH format 1/1a/1b will be described.

FIG. 11 illustrates a structure of an ACK/NACK channel for the case of anormal CP in a wireless communication system to which the presentinvention can be applied.

FIG. 11 illustrates a channel structure of a PUCCH intended fortransmission of HARQ ACK/NACK signal without using CQI.

The confirmation response information (not scrambled) of 1 bit and 2bits can be represented by a single HARQ ACK/NACK modulation symbol byusing BPSK and QPSK modulation scheme, respectively. Acknowledgement canbe encoded as ‘1’ while non-acknowledgement can be encoded as ‘0’.

When a control signal is transmitted within an allocated band,two-dimensional spreading is applied to increase multiplexing capacity.In other words, to increase the number of UEs or control channels thatcan be multiplexed, frequency and time domain spreading are applied atthe same time.

In order to spread the ACK/NACK signal in the frequency domain, afrequency domain sequence is used as a base sequence. For a frequencydomain sequence, Zadoff-Chu (ZC) sequence, which is one of the CAZACsequence, can be used.

In other words, for the case of the PUCCH format 1a/1b, the symbolmodulated by using BPSK or QPSK scheme is multiplied with a CAZACsequence (for example, ZC sequence) of length 12. For example, amodulation symbol d(0) is multiplied with the CAZAC sequence of lengthN, r(n), where n=0, 1, 2, . . . , N−1, to provide y(0), y(1), y(2), . .. , y(N−1). The y(0), y(1), . . . , y(N−1) symbols can be called a blockof symbols.

In this way, as a different cyclic shift (CS) is applied to the basesequence, ZC sequence, multiplexing of different UEs or control channelscan be implemented. The number of CS resources supported by SC-FDMAsymbols meant for PUCCH RBs to transmit the HARQ ACK/NACK signal is setby the cell-specific, upper-layer signaling parameter Δ_(shift)^(PUCCH).

After multiplication of a modulation symbol with the CAZAC sequence,block-wise spreading employing an orthogonal sequence is applied. Inother words, the ACK/NACK signal spread in the frequency domain isspread in the time domain by using the orthogonal spreading code. As theorthogonal spreading code (or orthogonal cover sequence) or orthogonalcover code (OCC), the Walsh-Hadamard sequence or Discrete FourierTransform (DTF) sequence can be used. For example, the ACK/NACK signalcan be spread through an orthogonal sequence of length 4 (w0, w1, w2,w3) with respect to four symbols. Also, the RS is also spread through anorthogonal sequence of length 2 or 3. And the above operation is calledorthogonal covering (OC).

For the ACK/NACK information or CDM of a demodulation reference signal,orthogonal covering based on the Walsh mode or DRF matrix can be used.

A DFT matrix is an N×N square matrix (where N is a natural number).

A DFT matrix can be defined as shown in Eq. 1.

$\begin{matrix}{W = \left( \frac{\omega^{jk}}{\sqrt{N}} \right)_{j,{k = 0},\; \ldots \mspace{11mu},{N - 1}}} & \left\lbrack {{Eq}.\; 1} \right\rbrack\end{matrix}$

Equation 1 can be represented as a matrix form as shown in Eq. 2.

$\begin{matrix}{{W = {\frac{1}{\sqrt{N}}\begin{bmatrix}1 & 1 & 1 & 1 & \cdots & 1 \\1 & \omega & \omega^{2} & \omega^{3} & \cdots & \omega^{N - 1} \\1 & \omega^{2} & \omega^{4} & \omega^{6} & \cdots & \omega^{2{({N - 1})}} \\1 & \omega^{3} & \omega^{6} & \omega^{9} & \cdots & \omega^{3{({N - 1})}} \\\vdots & \vdots & \vdots & \vdots & \ddots & \vdots \\1 & \omega^{N - 1} & \omega^{2{({N - 1})}} & \omega^{3{({N - 1})}} & \cdots & \omega^{{({N - 1})}{({N - 1})}}\end{bmatrix}}},{\omega = e^{- \frac{2{\pi 1}}{N}}}} & \left\lbrack {{Eq}.\; 2} \right\rbrack\end{matrix}$

in Eq. 2 denotes the primitive N-th root of unity.

A 2-point, 4-point, and 8-point DFT matrix are shown in Eqs. 3, 4, and5, respectively.

$\begin{matrix}{\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}} & \left\lbrack {{Eq}.\; 3} \right\rbrack \\{W = {\frac{1}{\sqrt{4}}\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- i} & {- 1} & i \\1 & {- 1} & 1 & {- 1} \\1 & i & {- 1} & {- i}\end{bmatrix}}} & \left\lbrack {{Eq}.\; 4} \right\rbrack \\{W = {\frac{1}{\sqrt{8}}\begin{bmatrix}\omega^{0} & \omega^{0} & \omega^{0} & \ldots & \omega^{0} \\\omega^{0} & \omega^{1} & \omega^{2} & \ldots & \omega^{7} \\\omega^{0} & \omega^{2} & \omega^{4} & \ldots & \omega^{14} \\\omega^{0} & \omega^{3} & \omega^{6} & \ldots & \omega^{21} \\\omega^{0} & \omega^{4} & \omega^{8} & \ldots & \omega^{28} \\\omega^{0} & \omega^{5} & \omega^{10} & \ldots & \omega^{35} \\\vdots & \vdots & \vdots & \ddots & \vdots \\\omega^{0} & \omega^{7} & \omega^{14} & \ldots & \omega^{49}\end{bmatrix}}} & \left\lbrack {{Eq}.\; 5} \right\rbrack\end{matrix}$

In the case of a normal CP, 3 consecutive SC-FDMA symbols located in themiddle of the 7 SC-FDMA symbols included within one slot carry thereference signal (RS), and the remaining 4 SC-FDMA symbols carry theACK/NACK signal. On the other hand, in the case of an extended CP, 2consecutive symbols in the middle thereof can carry the RS. The numberand the position of the symbols used for the RS can be varied accordingto a control channel, and the number and the position of the symbolsused for the ACK/NACK signal can also be changed according to thecontrol channel.

For the case of normal ACK/NACK information, the Walsh-Hadamard sequenceof length 4 is used, and for the case of shortened ACK/NACK informationand reference signal (RS), the DFT sequence of length 3 is used.

For the reference signal (RS) in the case of the extended CP, theHadamard sequence of length 2 is used.

Table 8 shows an orthogonal sequence (OC) [w(0) . . . w(N_(SF)^(PUCCH)−1] of length 4 for the PUCCH format 1a/1b.

TABLE 8 Sequence index Orthogonal sequences n_(oc)^(({tilde over (p)}))(n_(s)) [w(0) . . . w(N_(SF) ^(PUCCH) − 1)] 0 [+1+1 +1 +1] 1 [+1 −1 +1 −1] 2 [+1 −1 −1 +1]

Table 9 shows an orthogonal sequence [w(0) . . . w(N_(SF) ^(PUCCH)−1] oflength 3 for the PUCCH format 1a/1b.

TABLE 9 Sequence index Orthogonal sequences n_(oc)^(({tilde over (p)}))(n_(s)) [w(0) . . . w(N_(SF) ^(PUCCH) − 1)] 0 [1 11] 1 [1 e^(j2π/3) e^(j4π/3)] 2 [1 e^(j4π/3) e^(j2π/3)]

Table 10 shows an orthogonal sequence (OC) [w ^(({tilde over (p)}))(0) .. . w ^(({tilde over (p)}))(N_(RS) ^(PUCCH)−1] for the RS for the PUCCHformat 1/1a/1b.

TABLE 10 Sequence index n _(oc) ^(({tilde over (p)}))(n_(s)) Normalcyclic prefix Extended cyclic prefix 0 [1 1 1] [1 1] 1 [1 e^(j2π/3)e^(j4π/3)] [1 −1] 2 [1 e^(j4π/3) e^(j2π/3)] N/A

As described above, a plurality of UEs can be multiplexed through codedivision multiplexing (CDM) scheme by using the CS resource in thefrequency domain but OC resource in the time domain. In other words, theACK/NACK information and RS for a large number of UEs can be multiplexedon the same PUCCH RB.

With respect to the time domain spreading CDM, the number of spreadingcodes supporting the ACK/NACK information is limited by the number of RSsymbols. In other words, since the number of SC-FDMA symbols for RStransmission is smaller than the number of SC-FDMA symbols for ACK/NACKinformation transmission, multiplexing capacity of RS becomes smallerthan that of ACK/NACK information.

For example, in the case of a normal CP, ACK/NACK information can betransmitted from 4 symbols. In the case of an extended CP, 3 orthogonalspreading codes rather than 4 can be used for the ACK/NACK information;this is so because the number of RS transmission symbols is limited to 3and only three orthogonal spreading codes can be used for the RS.

Suppose in a subframe with a normal CP, 3 symbols from one slot are usedfor RS transmission and 4 symbols are used for ACK/NACK informationtransmission. If 6 cyclic shifts are available in the frequency domainand 3 orthogonal cover resources in the time domain can be used, theHARQ confirmation responses from a total of 18 different UEs can bemultiplexed within one PUCCH RB. Similarly, suppose in a subframe withan extended CP, 2 symbols from one slot are used for RS transmission and4 symbols are used for ACK/NACK information transmission. If 6 cyclicshifts are available in the frequency domain and 2 orthogonal coverresources in the time domain can be used, the HARQ confirmationresponses from a total of 12 different UEs can be multiplexed within onePUCCH RB.

Next, the PUCCH format 1 will be described. A scheduling request (SR) istransmitted in such a way that a UE may or may not request scheduling.An SR channel re-uses the ACK/NACK channel structure for the PUCCHformat 1a/1b and configured according to the On-Off Keying (OOK) schemebased on the ACK/NACK channel design. A reference signal is nottransmitted through the SR channel. Therefore, in the case of a normalCP, a sequence of length 7 is used while in the case of an extended CP,a sequence of length 6 is used. For the SR and ACK/NACK, a differentcyclic shift or orthogonal cover can be allocated.

FIG. 12 illustrates a method for multiplexing ACK/NACK and SR in awireless communication system to which the present invention can beapplied.

The structure of the SR PUCCH format 1 is the same as the structure ofthe ACK/NACK PUCCH format 1a/1b of FIG. 12.

A scheduling request (SR) is transmitted through the OOK scheme. Morespecifically, the UE transmits an SR which has a modulation symbold(0)=1 to request PUSCH resources (positive SR) but transmits nothing ifnot requesting scheduling (negative SR). Since the PUCCH structure forACK/NACK is re-used for SR, different resource indices within the samePUCCH region (namely, combinations of different cyclic shifts andorthogonal codes) can be allocated to the SR (PUCCH format 1) or HARQACK/NACK (PUCCH format 1a/1b). The PUCCH resource index to be used bythe UE for SR transmission is set by UE-specific upper layer signaling.

In case the UE needs to transmit a positive SR from a subframe scheduledfor CQI transmission, the UE is allowed to drop CQI and to transmit theSR only. Similarly, if the UE needs to transmit the SR and the SRS atthe same time, the UE is allowed to drop the CQI and to transmit the SRonly.

In case the SR and the ACK/NACK are generated in the same subframe, theUE transmits the ACK/NACK signal on the SR PUCCH resource allocated forpositive SR. In the case of negative SR, the UE transmits the ACK/NACKsignal on the ACK/NACK resources allocated.

FIG. 12 shows constellation mapping for simultaneous transmission of anACK/NACK signal and an SR. More specifically, FIG. 12 illustrates thatNACK signal (or, in the case of two MIMO codewords, NACK, NACK) ismapped being modulated to +1. Accordingly, occurrence of discontinuoustransmission (DTX) is treated as NACK.

For SR and persistent scheduling, the ACK/NACK resources comprising CS,OC, and physical resource blocks (PRBs) can be allocated to the UEthrough radio resource control (RRC). On the other hand, for the purposeof dynamic ACK/NACK transmission and non-persistent scheduling, ACK/NACKresources can be allocated implicitly to the UE through the lowest CCEindex of the PUCCH corresponding to the PDSCH.

The UE can transmit the SR if resources for uplink data transmission areneeded. In other words, transmission of the SR is event-triggered.

The SR PUCCH resources are configured by upper layer signaling exceptfor the case the SR is transmitted together with the HARQ ACK/NACK byusing the PUCCH format 3. In other words, the SR PUCCH resources areconfigured by the ScheduleingRequestConfig information elementtransmitted through the radio resource control (RRC) message (forexample, an RRC connection reconfiguration message).

Table 11 shows the ScheduleingRequestConfig information element.

TABLE 11 -- ASN1START SchedulingRequestConfig ::= CHOICE { release NULL,setup SEQUENCE { sr-PUCCH-ResourceIndex INTEGER (0..2047),sr-ConfigIndex INTEGER (0..157), dsr-TransMax ENUMERATED { n4, n8, n16,n32, n64, spare3, spare2, spare1} } } SchedulingRequestConfig-v1020 ::=SEQUENCE { sr-PUCCH-ResourceIndexP1-r10 INTEGER (0..2047) OPTIONAL } --ASN1STOP

Table 12 shows the fields included in the SchedulingRequestConfiginformation element.

TABLE 12 SchedulingRequestConfig field descriptions dsr-TransMaxParameter for SR transmission. n4 represents four times of transmission,n8 eight times of transmission, and so on. sr-ConfigIndex Parameter(I_(SR)). 156 and 157 values are not defined in the release 8.sr-PUCCH-ResourceIndex, sr-PUCCH-ResourceIndexP1 Parameters for antennaport p0 and 01, respectively (n_(PUCCH, SRI) ^((1, p))). E- UTRANconfigures sr-PUCCH-ResourceIndexP1 only when sr- PUCCHResourceIndex isset up.

With reference to FIG. 12, the UE receives sr-PUCCH-ResourceIndexparameter for SR transmission through an RRC message and sr-ConfigIndexparameter (I_(SR)) indicating the SR configuration index. Thesr-ConfigIndex parameter can be used to configure SR_(PERIODICITY) whichindicates the period at which the SR is transmitted and N_(OFFSET,SR)which indicates a subframe from which the SR is transmitted. In otherwords, the SR is transmitted from a particular subframe repeatedperiodically according to I_(SR) given by the upper layer. Also,subframe resources and CDM/FDM (Frequency Division Multiplexing)resources can be allocated to the resources for SR.

Table 13 represents an SR transmission period and an SR subframe offsetaccording to an SR configuration index.

TABLE 13 SR configuration Index SR periodicity (ms) SR subframe offsetI_(SR) SR_(PERIODICITY) N_(OFFSET, SR) 0-4 5 I_(SR)  5-14 10 I_(SR) − 5 15-34 20 I_(SR) − 15 35-74 40 I_(SR) − 35  75-154 80 I_(SR) − 75 155-1562  I_(SR) − 155 157 1  I_(SR) − 157

Buffer Status Reporting (BSR)

FIG. 13 illustrates an MAC PDU used by an MAC entity in a wirelesscommunication system to which the present invention can be applied.

With reference to FIG. 13, the MAC PDU includes an MAC header, at leastone MAC service data unit (SDU), and at least one MAC control element;and may further comprise padding. Depending on the situation, at leastone of the MAC SDU and the MAC control element may not be included inthe MAC PDU.

As shown in FIG. 13, the MAC control element usually precedes the MACSDU. And the size of the MAC control element can be fixed or varied. Incase the size of the MAC control element is variable, whether the sizeof the MAC control element has been increased can be determined throughan extended bit. The size of the MAC SDU can also be varied.

The MAC header can include at least one or more sub-headers. At thistime, at least one or more sub-headers included in the MAC headercorrespond to the MAC SDU, MAC control element, and padding,respectively, which the order of the sub-headers is the same as thedisposition order of the corresponding elements. For example, as shownin FIG. 10, if the MAC PDU includes an MAC control element 1, an MACcontrol element 2, a plurality of MAC SDUs, and padding, sub-headers canbe disposed in the MAC header so that a sub-header corresponding to theMAC control element 1, a sub-header corresponding to the MAC controlelement 2, a plurality of sub-headers corresponding respectively to theplurality of MAC SDUs, and a sub-header corresponding to padding can bedisposed according to the corresponding order.

The sub-header included in the MAC header, as shown in FIG. 10, caninclude 6 header fields. More specifically, the sub-header can include 6header fields of R/R/E/LCID/F/L.

As shown in FIG. 10, for the sub-header corresponding to the MAC controlelement of a fixed size and the sub-header corresponding to the last oneamong the data fields included in the MAC PDU, sub-headers including 4header fields can be used. Therefore, in case a sub-header includes 4fields, the four fields can be R/R/E/LCID.

FIGS. 14 and 15 illustrate a sub-header of an MAC PDU in a wirelesscommunication system to which the present invention can be applied.

In the following, each field is described with reference to FIGS. 14 and15.

1) R: Reserved bit, not used.

2) E: Extended bit, indicating whether the element corresponding to asub-header is extended. For example, if E field is ‘0’, the elementcorresponding to the sub-header is terminated without repetition; if Efield is ‘1’, the element corresponding to the sub-header is repeatedone more time and the length of the element is increased twice of theoriginal length.

3) LCID: Logical Channel Identification. This field is used foridentifying a logical channel corresponding to the MAC SDU oridentifying the corresponding MAC control element and padding type. Ifthe MAC SDU is related to a sub-header, this field then indicates alogical channel which the MAC SDU corresponds to. If the MAC controlelement is related to a sub-header, then this field can describe whatthe MAC control element is like.

Table 14 shows the LCID values for DL-SCH.

TABLE 14 Index LCID values 00000 CCCH 00001-01010 Identity of thelogical channel 01011-11001 Reserved 11010 Long DRX Command 11011Activation/Deactivation 11100 UE Contention Resolution Identity 11101Timing Advance Command 11110 DRX Command 11111 Padding

Table 15 shows LCID values for UL-SCH.

TABLE 15 Index LCID values 00000 CCCH 00001-01010 Identity of thelogical channel 01011-11000 Reserved 11001 Extended Power HeadroomReport 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR11101 Short BSR 11110 Long BSR 11111 Padding

In the LTE/LTE-A system, a UE can report its buffer state to the networkby setting an index value for any of a truncated BSR in the LCID field,a short BSR, and a long BSR.

The index values and a mapping relationship of the LCID values of Tables14 and 15 are shown for an illustrative purpose, and the presentinvention is not limited to the example.

4) F: Format field. Represents the size of the L field

5) L: Length field. Represents the size of the MAC SDU corresponding toa sub-header and the size of the MAC control element. If the size of theMAC SDU corresponding to a sub-header or the size of the MAC controlelement is equal to or smaller than 127 bits, 7 bits of the L field canbe used (FIG. 14(a)) and 15 bits of the L field can be used for theother cases (FIG. 14(b)). In case the size of the MAC control elementvaries, the size of the MAC control element can be defined through the Lfield. In case the size of the MAC control element is fixed, the F andthe L field may be omitted as shown in FIG. 15 since the size of the MACcontrol element can be determined without defining the size of the MACcontrol element through the L field.

FIG. 16 illustrates a format of an MAC control element for reporting abuffer state in a wireless communication system to which the presentinvention can be applied.

In case the truncated BSR and short BSR are defined in the LCID field,the MAC control element corresponding to a sub-header can be configuredto include a logical channel group identification (LCG ID) field and abuffer size field indicating a buffer state of the logical channel groupas shown in FIG. 16(a). The LCG ID field is intended to identify alogical channel group to which to report a buffer state and can have thesize of two bits.

The buffer size field is intended to identify the total amount of dataavailable for all of the logical channels belonging to a logical channelgroup after the MAC PDU is created. The available data include all ofthe data that can be transmitted from the RLC layer and the PDCP layer,and the amount of data is represented by the number of bytes. The buffersize field can have the size of 6 bits.

In case a long BSR is defined for the LCID field of a sub-header, theMAC control element corresponding to a sub-header can include 4 buffersize fields indicating buffer states of the four groups having LCG IDsranging from 0 to 3 as shown in FIG. 16(b). Each buffer size field canbe used to identify the total amount of data available for each logicalchannel group.

Carrier Aggregation in General

Communication environments considered in the embodiments of the presentinvention includes all of multi-carrier supporting environments. Inother words, a multi-carrier system or a carrier aggregation systemaccording to the present invention refers to the system utilizingaggregation of one or more component carriers having bandwidth narrowerthan target bandwidth to establish a broadband communicationenvironment.

A multi-carrier according to the present invention refers to aggregationof carriers, and the carrier aggregation in this sense refers to notonly the aggregation of contiguous carriers but also the aggregation ofnon-contiguous carriers. Also, the numbers of component carriersaggregated for downlink and uplink transmission can be set differentlyfrom each other. The case where the number of downlink componentcarriers (hereinafter, it is called ‘DL CC’) is the same as the numberof uplink component carriers (hereinafter, it is called ‘UL CC’) iscalled symmetric aggregation, whereas it is called asymmetricaggregation otherwise. The term of carrier aggregation may be usedinterchangeably with bandwidth aggregation and spectrum aggregation.

Carrier aggregation composed of a combination of two or more componentcarriers is intended to support bandwidth of up to 100 MHz for the caseof the LTE-A system. When one or more carriers having narrower bandwidththan target bandwidth are combined, the bandwidth of the carrier to becombined can be limited to the bandwidth defined by an existing systemto maintain compatibility with the existing IMT system. For example,while the existing system supports bandwidth of 1.4, 3, 5, 10, 15, and20 MHz, the 3GPP LTE-A system can support bandwidth larger than 20 MHzby using a combination of the predefined bandwidth to maintaincompatibility with the existing system. Also, a carrier aggregationsystem according to the present invention may support carrieraggregation by defining new bandwidth independently of the bandwidthused in the existing system.

The LTE-A system introduces a concept of a cell for management of radioresources.

The carrier aggregation environment can be referred to as a multiplecell environment. A cell is defined as a combination of a pair of a DLCC and an UL CC, but the UL CC is not an essential element. Therefore, acell can be composed of downlink resources only or a combination ofdownlink and uplink resources. In case a particular UE is linked to onlyone configured serving cell, one DL CC and one UL CC are employed.However, if the particular UE is linked to two or more configuredserving cells, as many DL CCs as the number of cells are employed whilethe number of UL CCs can be equal to or smaller than the number of DLCCs.

Meanwhile, the DL CCs and the UL CCs can be composed in the oppositeway. In other words, in case a particular UE is linked to a plurality ofconfigured serving cells, a carrier aggregation environment which hasmore UL CCs than DL CCs can also be supported. In other words, carrieraggregation can be understood as a combination of two or more cellshaving different carrier frequencies (center frequencies of the cells).At this time, the term of ‘cell’ should be distinguished from the ‘cell’usually defined as a region covered by an eNB.

The LTE-A system defines a primary cell (PCell) and a secondary cell(SCell). A PCell and an SCell can be used as a serving cell. A UE beingin an RRC_CONNECTED state but not being configured for carrieraggregation or not supporting carrier aggregation can be linked to oneor more serving cells, and the entire serving cells include a PCell andone or more SCells.

A serving cell (PCell and SCell) can be configured through an RRCparameter. PhysCellId is a physical layer identifier of a cell, havingan integer value ranging from 0 to 503. SCellIndex is a short identifierused for identifying an SCell, having an integer value ranging from 1 to7. ServCellIndex is a short identifier used for identifying a servingcell (PCell or SCell), having an integer value ranging from 0 to 7. Thevalue of 0 is applied to a PCell, and SCellIndex is pre-assigned to beapplied to an SCell. In other words, the cell which has the smallestcell ID (or cell index) of ServCellIndex becomes the PCell.

A PCell refers to a cell operating on a primary frequency (or a primaryCC). A PCell can be used for an UE to carry out initial connectionestablishment or connection re-establishment; a PCell may refer to thecell indicated during a handover procedure. Also, a PCell refers to thecell which plays a central role for control-related communication amongconfigured serving cells in a carrier aggregation environment. In otherwords, a UE is capable of receiving and transmitting a PUCCH onlythrough its own PCell; also, the UE can obtain system information ormodify a monitoring procedure only through the PCell. The E-UTRAN(Evolved Universal Terrestrial Radio Access Network) may change only thePCell by using an RRC connection reconfiguration message(RRCConnectionReconfiguration) of an upper layer including mobilitycontrol information (mobilityControlInfo) so that the UE supportingcarrier aggregation environments can carry out a handout procedure.

An SCell refers to a cell operating on a secondary frequency (or asecondary CC). For a particular UE, only one PCell is allocated, but oneor more SCells can be allocated. An SCell can be composed afterconfiguration for an RRC connection is completed and can be used toprovide additional radio resources. A PUCCH does not exist in theremaining cells except for PCells among the serving cells configured fora carrier aggregation environment, namely, SCells. When adding an SCellto a UE supporting a carrier aggregation environment, the E-UTRAN canprovide all of the system information related to the operation of a cellin the RRC_CONNECTED state through a dedicated signal. Modification ofsystem information can be controlled according to release and additionof a related SCell, and at this time, an RRC connection reconfigurationmessage (RRCConnectionReconfiguration) message of an upper layer can beused. The E-UTRAN, instead of broadcasting a signal within an SCell, maycarry out dedicated signaling using parameters different for each UE.

After the initial security activation process is started, the E-UTRANmay form a network including one or more SCells in addition to a PCelldefined in the initial step of a connection establishment process. In acarrier aggregation environment, a PCell and an SCell can operate as anindependent component carrier. In the embodiment below, a primarycomponent carrier (PCC) can be used in the same context as the PCell,while a secondary component carrier (SCC) can be used in the samecontext as the SCell.

FIG. 17 illustrates one example of a component carrier and carrieraggregation in a wireless communication system to which the presentinvention can be applied.

FIG. 17(a) shows a single carrier structure defined in the LTE system.Two types of component carriers are used: DL CC and UL CC. A componentcarrier can have frequency bandwidth of 20 MHz.

FIG. 17(b) shows a carrier aggregation structure used in the LTE Asystem. FIG. 17(b) shows a case where three component carriers havingfrequency bandwidth of 20 MHz are aggregated. In this example, 3 DL CCsand 3 UL CCs are employed, but the number of DL CCs and UL CCs is notlimited to the example. In the case of carrier aggregation, the UE iscapable of monitoring 3 CCs at the same time, capable of receiving adownlink signal/data and transmitting an uplink signal/data.

If a particular cell manages N DL CCs, the network can allocated M (M≦N)DL CCs to the UE. At this time, the UE can monitor only the M DL CCs andreceive a DL signal from the M DL CCs. Also, the network can assignpriorities for L (L≦M≦N) DL CCs so that primary DL CCs can be allocatedto the UE; in this case, the UE has to monitor the L DL CCs. This schemecan be applied the same to uplink transmission.

Linkage between a carrier frequency of downlink resources (or DL CC) anda carrier frequency of uplink resources (or UL CC) can be designated byan upper layer message such as an RRC message or system information. Forexample, according to the linkage defined by system information blocktype 2 (SIB2), a combination of DL resources and UL resources can bedetermined. More specifically, the linkage may refer to a mappingrelationship between a DL CC through which a PDCCH carrying an UL grantis transmitted and an UL CC that uses the UL grant; or a mappingrelationship between a DL CC (or an UL CC) through which data for HARQsignal are transmitted and an UL CC (or a DL CC) through which a HARQACK/NACK signal is transmitted.

Uplink Resource Allocation Procedure

In the case of the 3GPP LTE/LTE-A system, a method for data transmissionand reception based on scheduling of an eNB is used to maximizeutilization of radio resources. This again implies that in case a UE hasdata to transmit, the UE requests the eNB to allocate uplink resourcesin the first place and is capable of transmitting data by using only theuplink resources allocated by the eNB.

FIG. 18 illustrates an uplink resource allocation process of a UE in awireless communication system to which the present invention can beapplied.

For efficient use of radio resources in uplink transmission, an eNBneeds to know which data and how much of the data to transmit to eachUE. Therefore, the UE transmits to the eNB the information about uplinkdata that the UE attempts to transmit directly, and the eNB allocatesuplink resources to the corresponding UE in accordance to the UE'stransmission. In this case, the information about uplink data that theUE transmits to the eNB is the amount of uplink data stored in the UE'sbuffer, which is called buffer status report (BSR). When radio resourceson the PUSCH are allocated during a current TTI and a reporting event istriggered, the UE transmits the BSR by using the MAC control element.

FIG. 18(a) illustrates an uplink resource allocation process for actualdata in case the uplink radio resources for buffer status reporting arenot allocated to the UE. In other words, in the case of a UE making atransition from the DRX mode to an active mode, since no data resourcesare allocated beforehand, the UE has to request resources for uplinkdata, starting with SR transmission through the PUCCH, and in this case,an uplink resource allocation procedure of five steps is employed.

FIG. 18(a) illustrates the case where the PUSCH resources fortransmitting BSR are not allocated to the UE, and the UE first of alltransmits a scheduling request (SR) to the eNB to receive PUSCHresources S1801.

The scheduling request is used for the UE to request the eNB to allocatethe PUSCH resources for uplink transmission in case radio resources arenot scheduled on the PUSCH during a current TTI although a reportingevent has occurred. In other words, when a regular BSR has beentriggered but uplink radio resources for transmitting the BSR to the eNBare not allocated to the UE, the UE transmits the SR through the PUCCH.Depending on whether the PUCCH resources for SR have been configured,the UE may transmit the SR through the PUCCH or starts a random accessprocedure. More specifically, the PUCCH resources through the SR can betransmitted are set up by an upper layer (for example, the RRC layer) ina UE-specific manner, and the SR configuration include SR periodicityand SR sub-frame offset information.

If the UE receives from the eNB an UL grant with respect to the PUSCHresources for BSR transmission S1803, the UE transmits the BSR to theeNB, which has been triggered through the PUSCH resources allocated bythe UL grant S1805.

By using the BSR, the eNB checks the amount of data for the UE toactually transmit through uplink transmission and transmits to the UE anUL grant with respect to the PUSCH resources for transmission of actualdata S1807. The UE, which has received the UL grant meant fortransmission of actual data, transmits to the eNB actual uplink datathrough the allocated PUSCH resources S1809.

FIG. 18(b) illustrates an uplink resource allocation process for actualdata in case the uplink radio resources for buffer status reporting areallocated to the UE.

FIG. 18(b) illustrates the case where the PUSCH resources for BSRtransmission have already been allocated to the UE; the UE transmits theBSR through the allocated PUSCH resources and transmits a schedulingrequest to the eNB along with the BSR transmission S1811. Next, by usingthe BSR, the eNB check the amount of data that the UE actually transmitsthrough uplink transmission and transmits to the UE an UL grant withrespect to the PUSCH resources for transmission of actual data S1813.The UE, which has received an UL grant for transmission of actual data,transmits actual uplink data to the eNB through the allocated PUSCHresources S1815.

FIG. 19 illustrates latency in a C-plane required in the 3GPP LTE-Asystem to which the present invention can be applied.

With reference to FIG. 19, the 3GPP LTE-A standard requires thattransition time from the IDLE mode (the state where an IP address isassigned) to the connected mode is less than 50 ms. At this time, thetransition time includes setting time (which excludes S1 transmissiondelay time) for the user plane (U-Plane). Also, the transition time fromthe dormant state to the active state within the connected mode isrequired to be less than 10 ms.

Transition from the dormant state to the active state can be generatedaccording to the following four scenarios.

-   -   Uplink initiated transition, synchronized    -   Uplink initiated transition, unsynchronized    -   Downlink initiated transition, synchronized    -   Downlink initiated transition, unsynchronized

FIG. 20 illustrates transition time of a synchronized UE from a dormantstate to an active state required in the 3GPP LTE-A system to which thepresent invention can be applied.

FIG. 20 illustrates the previous three steps of the uplink resourceallocation procedure of FIG. 18 (the case where uplink radio resourcesfor BSR are allocated). In the LTE-A system, delay time as shown inTable 16 is required for uplink resource allocation.

Table 16 shows transition time from the dormant state to the activestate initiated by uplink transmission for a synchronized UE, requiredby the LTE-A system.

TABLE 16 Component Description Time [ms] 1 Average delay to next SRopportunity 0.5/2.5 (1 ms/5 ms PUCCH cycle) 2 UE sends SchedulingRequest 1 3 eNB decodes Scheduling Request and 3 generates theScheduling Grant 4 Transmission of Scheduling Grant 1 5 UE ProcessingDelay (decoding of 3 scheduling grant + L1 encoding of UL data) 6Transmission of UL data 1 Total delay  9.5/11.5

With reference to FIG. 20 and Table 16, an average delay of 0.5 ms/2.5ms is required due to the PUCCH period having 1 ms/5 ms PUCCH cycle, and1 ms is required for the UE to transmit SR. And the eNB requires 3 ms todecode the SR and to generate a scheduling grant, and another 1 ms totransmit the scheduling grant. And the UE requires 3 ms to decode thescheduling grant and to encode uplink data in the L1 layer, and another1 ms to transmit the uplink data.

Thus a total of 9.5/15.5 ms is required for the UE to complete theprocess of transmitting uplink data.

Random Access Channel (RACH) Procedure

FIG. 21a and FIG. 21b illustrate one example of a random accessprocedure in the LTE system.

The random access procedure is carried out during initial connection inthe RRC_IDLE state, initial connection after radio link failure,handover which requires the random access procedure, and upon occurrenceof uplink or downlink data requiring the random access procedure whilein the RRC_CONNECTED state. Part of the RRC message such as the RRCconnection request message, cell update message, and UTRAN registrationarea (URA) update message is also transmitted through the random accessprocedure. Logical channels such as a common control channel (CCCH),dedicated control channel (DCCH), and dedicated traffic channel (DTCH)can be mapped to a physical channel, random access channel (RACH). TheRACH is mapped to a physical channel, physical random access channel(PRACH).

If the MAC layer of the UE commands the UE's physical layer to performPRACH transmission, the UE's physical layer first selects one accessslot and one signature and transmits a PRACH preamble through uplinktransmission. The random access procedure is divided into acontention-based random access procedure and a non-contention basedrandom access procedure.

FIG. 21a illustrates one example of a contention-based random accessprocedure, and FIG. 21b illustrates one example of a non-contentionbased random access procedure.

First, the contention-based random access procedure will be describedwith reference to FIG. 21 a.

The UE receives information about random access from the eNB throughsystem information and stores the received information. Afterwards, incase random access is needed, the UE transmits a random access preamble(which is also called a message 1) to the eNB S2101.

If the eNB receives a random access preamble from the UE, the eNBtransmits a random access response message (which is also called amessage 2) to the UE S2102. More specifically, downlink schedulinginformation about the random access response message, being CRC-maskedwith a random access-ratio network temporary identifier (RA-RNTI), canbe transmitted on an L1 or L2 control channel (PDCCH). The UE, which hasreceived a downlink scheduling signal masked with an RA-RNTI, canreceive the random access response message from a physical downlinkshared channel (PDSCH) and decode the received message. Afterwards, theUE checks the random access response message as to whether random accessresponse information for the UE exists.

The UE can determine existence of random access response information bychecking existence of a random access preamble ID (RAID) with respect tothe preamble that the UE has transmitted.

The random access response information includes timing alignment (TA)indicating timing offset information for synchronization, radio resourceallocation information used for uplink transmission, and a temporaryC-RNTI for identifying UEs.

If receiving random access response information, the UE carries outuplink transmission (which is also called a message 3) to an uplinkshared channel (UL-SCH) according to radio resource allocationinformation included in the response information S2103. At this time,uplink transmission may be described as scheduled transmission.

After receiving the uplink transmission from the UE, the eNB transmits amessage for contention resolution (which is also called a message 4) tothe UE through a downlink shared channel (DL-SCH) S2104.

Next, a non-contention based random access procedure will be describedwith reference to FIG. 21 b.

Before the UE transmits a random access preamble, the eNB allocates anon-contention random access preamble to the UE S2111.

The non-contention random access preamble can be allocated through ahandover command or dedicated signaling such as signaling through thePDCCH. In case non-contention random access preamble is allocated to theUE, the UE transmits the allocated non-contention random access preambleto the eNB S2112.

Afterwards, similarly to the S2102 step of the contention-based randomaccess procedure, the UE can transmit a random access response (which isalso called a message 2) to the UE S2113.

Although the HARQ is not applied for a random access response during therandom access procedure described above, the HARQ can be applied foruplink transmission with respect to a random access response or amessage for contention resolution. Therefore, the UE doesn't have totransmit ACK or NACK signal for the case of the random access response.

Uplink Reference Signal

FIG. 22 illustrates another example of a structure of an uplinksubframe.

With reference to FIG. 22, the UE transmits a sounding reference signalperiodically or non-periodically to estimate a channel for an uplinksub-band excluding the band in which the PUSCH is transmitted or toobtain information of a channel corresponding to the whole uplinkbandwidth (wide band). The period of SRS transmission is determinedthrough upper layer signaling; transmission of a non-periodic soundingreference signal is specified by the eNB by using the ‘SRS request’field of the PDCCH uplink/downlink DCI format or carried out as the eNBtransmits a triggering message. As shown in FIG. 22, the region to whichthe sounding reference signal can be transmitted within a subframe isthe interval containing the SC-FDMA symbol located at the last positionon the time axis within the subframe. The sounding reference signals ofvarious UEs transmitted to the last SC-FDMA symbol of the same subframecan be identified according to the respective frequencies. Differentfrom the PUSCH, a sounding reference signal does not carry out DFT(Discrete Fourier Transform) calculations for conversion to an SC-FDMAsymbol and is transmitted without using a precoding matrix employed bythe PUSCH.

Likewise, the region to which a demodulation reference signal (DMRS) istransmitted within a subframe is the interval containing the SC-FDMAsymbol located at the center of each slot on the time axis and in thesame way, the DMRS is transmitted through a data transmission band inthe frequency domain. For example, for a subframe to which a normalcyclic shift is applied, the DMRS is transmitted from the 4-th SC-FDMAsymbol and the 11-th SC-FDMA symbol.

The DMRS can be combined with transmission of the PUSCH or the PUCCH.The sounding reference signal is a reference signal that the UEtransmits to the eNB for uplink scheduling. The eNB estimates an uplinkchannel through the received sounding reference signal and uses theestimated uplink channel for uplink scheduling. The sounding referencesignal is not combined with transmission of the PUSCH or the PUCCH. Thesame type of a base sequence can be used for the DMRS and the soundingreference signal. Meanwhile, the precoding matrix applied to the DMRSfor uplink multi-antenna transmission can be the same as the precodingmatrix applied to the PUSCH.

FIG. 23 illustrates a signal processing procedure for transmitting anuplink reference signal.

As shown in FIG. 23, data generate a signal in the time domain and aretransmitted through IFFT after frequency mapping through a DFT precoder.On the other hand, a reference signal does not go through the processemploying the DFT precoder. More specifically, right after the referencesignal is generated in the frequency domain S2310, the reference signalgoes through a localized mapping process S2320, an IFFT process S2330,and a cyclic prefix attach process S2340 sequentially, after which thereference signal is transmitted.

FIG. 24 illustrates a structure of a subframe for transmittingdemodulation reference signal (DMRS).

FIG. 24(a) illustrates a structure of a subframe for transmitting a DMRSfor the case of a normal CP, and FIG. 24(b) illustrates a structure of asubframe for transmitting a DMRS for the case of an extended CP. Withreference to FIG. 24(a), in the case of a normal CP, a DMRS istransmitted through the 4-th and the 11-th SC-FDMA symbols; withreference to FIG. 24(b), in the case of an extended CP, the DMRS istransmitted through the 3-rd and the 9-th SC-FDMA symbol.

Demodulation Reference Signal with Respect to PUSCH

A reference signal with respect to the PUSCH is determined as follows.

The reference signal sequence r_(PUSCH) ^((λ))(•) with respect to thePUSCH corresponds to a layer index and defined by the following Eq. 6.

r _(PUSCH) ^((λ))(m·M _(sc) ^(RS) +n)=w ^((λ))(m)r _(u,v) ^((α) ^(λ)⁾(n),  [Eq. 6]

where m and n are given as

$\begin{matrix}{{m = 0},1} \\{{n = 0},\ldots \mspace{11mu},{M_{sc}^{RS} - 1}}\end{matrix},\quad$

and M_(sc) ^(RS)=M_(sc) ^(PUSCH).

In case an upper layer parameter ‘Activate-DMRS-with OCC’ is not set upor a temporary C-RNTI is used for transmitting the DCI related to themost recent uplink transmission, an orthogonal sequence w^((λ))) (m) isset so that [w^(λ)(0) w^(λ)(1)]=[1 1] to comply with the DCI format 0.On the other hand, the orthogonal sequence may be set up as shown inTable 17 according to a cyclic shift field included in the DCI relatedto the most recent uplink transmission with respect to a transport blockrelated to the transmission of the corresponding PUSCH.

[w^(λ)(0) w^(λ)(1)] represents an orthogonal sequence corresponding to alayer index λ; in particular, w^((λ))(0) corresponds to a value appliedto the first slot of the layer index λ, and w^((λ))(1) corresponds to avalue applied to the second slot of the layer index λ.

Table 17 shows a correspondence relationship between a cyclic shiftfield within the DCI related to uplink transmission and n_(DMRS,λ) ⁽²⁾and [w^(λ)(0) w^(λ)(1)].

TABLE 17 Cyclic Shift Field in uplink-related n_(DMRS, λ) ⁽²⁾[w^((λ))(0) w^((λ))(1)] DCI format [3] λ = 0 λ = 1 λ = 2 λ = 3 λ = 0 λ =1 λ = 2 λ = 3 000 0 6 3 9 [1 1] [1 1] [1 −1] [1 −1] 001 6 0 9 3 [1 −1][1 −1] [1 1] [1 1] 010 3 9 6 0 [1 −1] [1 −1] [1 1] [1 1] 011 4 10 7 1 [11] [1 1] [1 1] [1 1] 100 2 8 5 11 [1 1] [1 1] [1 1] [1 1] 101 8 2 11 5[1 −1] [1 −1] [1 −1] [1 −1] 110 10 4 1 7 [1 −1] [1 −1] [1 −1] [1 −1] 1119 3 0 6 [1 1] [1 1] [1 −1] [1 −1]

The cyclic shift value α_(λ) within the slot n_(s) is defined by thefollowing Eq. 7, and n_(cs,λ) is defined as shown in Eq. 8.

α_(λ)=2πn _(cs,λ)/12  [Eq. 7]

n _(cs,λ)=(n _(DMRS) ⁽¹⁾ +n _(DMRS,λ) ⁽²⁾ +n _(PN)(n _(s)))mod 12,  [Eq.8]

where n_(DMRS) ⁽¹⁾ is determined by an upper layer parameter‘cyclicShift’ and describes the correspondence relationship between theparameter value shown in Table 18 and n_(DMRS) ⁽¹⁾.

TABLE 18 cyclicShift n_(DMRS) ⁽¹⁾ 0 0 1 2 2 3 3 4 4 6 5 8 6 9 7 10

n_(DMRS,λ) ⁽²⁾ is determined by a cyclic shift value for the DMRS fieldwithin the DCI related to the most recent uplink transmission of atransport block corresponding to the transmission of the PUSCH, andn_(DMRS,λ) ⁽²⁾ value is shown in Table 18.

With reference to Table 18, in case a downlink physical control channel(PDCCH) including the DCI related to uplink transmission is nottransmitted on the same transmission block, or in case the initial PUSCHis semi-persistently scheduled in the same transport block, or in casethe initial PUSCH is scheduled according to a random access responsegrant in the same transport block, n_(DMRS) ⁽¹⁾ can have the value asshown in the first column of Table 18.

n_(PN)(n_(s)) can be defined by the following Eq. 9.

n _(PN)(n _(s))=Σ_(i=0) ⁷(8N _(symb) ^(UL) ·n _(s) +i)·2^(i),  [Eq. 9]

where c(i) is a pseudo-random sequence and is a cell-specific value. Apseudo-random sequence generator can be initialized to

$c_{init} = {{\left\lfloor \frac{N_{ID}^{cell}}{30} \right\rfloor \cdot 2^{5}} + f_{ss}^{PUSCH}}$

at the start of a radio frame.

The vector of a reference signal can be precoded as shown in Eq. 10.

$\begin{matrix}{{\begin{bmatrix}{\overset{\sim}{r}}_{PUSCH}^{(0)} \\\vdots \\{\overset{\sim}{r}}_{PUSCH}^{({P - 1})}\end{bmatrix} = {W\begin{bmatrix}r_{PUSCH}^{(0)} \\\vdots \\r_{PUSCH}^{({v - 1})}\end{bmatrix}}},} & \left\lbrack {{Eq}.\; 10} \right\rbrack\end{matrix}$

where P represents the number of antenna ports used for transmission ofthe PUSCH. When one antenna port is employed for transmission of thePUSCH, P=1, W=1, and υ=1. In the case of spatial multiplexing, P=2 orP=4, and the precoding matrix W can be used in the same manner as usedfor precoding of the PUSCH within the same subframe.

A physical mapping method for an uplink reference signal in the PUSCHtransmission is as follows.

For each antenna port used for PUSCH transmission, the {tilde over(r)}_(PUSCH) ^(({tilde over (p)}))(•) sequence is multiplied with anamplitude scaling factor β_(PUSCH) and starting from {tilde over(r)}_(PUSCH) ^(({tilde over (p)}))(0), mapped to a sequence. Therelationship between a physical resource block set used for the mappingprocess and the index {tilde over (P)} and the antenna port number P isthe same as the transmission of the corresponding PUSCH. For a resourceelement (RE) with an index (k,l), in the case of a normal CP, l=3; inthe case of an extended CP, l=2; and {tilde over (r)}_(PUSCH)^(({tilde over (p)}))(•) is mapped in an increasing order of k and thenmapped in an increasing order of the slot number.

Uplink/Downlink Scheduling in the TDD System

Since downlink/uplink subframe structure in the TDD system is differentfor each uplink-downlink configuration, transmission time of the PUSCHand PHICH is set up differently according to the configuration, andtransmission time of the PUSCH and PHICH is set up differently accordingto the subframe index (or number).

The LTE system defines the uplink/downlink timing relationship among thePUSCH, the PDCCH preceding the PUSCH, and the PHICH through which adownlink HARQ ACK/NACK signal corresponding to the PUSCH is transmitted.

Table 19 shows transmission timing of the PDCCH and the PUSCHcorresponding to the PDCCH according to uplink-downlink configurations.

TABLE 19 TDD UL/DL Config- subframe number n uration 0 1 2 3 4 5 6 7 8 90 4 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

With reference to Table 19, in the case of uplink-downlinkconfigurations 1 to 6, when the UE receives an UL grant through thePDCCH from the eNB in the n-th downlink subframe or needs to re-transmitthe PHICH after receiving the PHICH, the UE transmits the PUSCH,according to the downlink subframe index with which the PDCCH (or PHICH)has been transmitted, from the (n+k)-th uplink subframe corresponding tothe index. At this time, the k value follows as shown in Table 19.

In the case of uplink-downlink configuration 0, the UE carries outtransmission of the PUSCH according to the relationship shown in Table 1indicated by I_(PHICH) which is determined by the uplink index valuewithin the uplink DCI format, the number of a downlink subframe fromwhich the PHICH is transmitted, and the number of an uplink subframetransmitted to an upper layer or from which the PUSCH is transmitted.The UE may transmit the PUSCH from the (n+7)-th uplink subframe; or theUE may transmit the PUSCH to both of the uplink subframe specifiedaccording to Table 19 and the (n+7)-th uplink subframe.

Meanwhile, if the UE receives the PHICH including the HARQ ACK/NACKsignal from the eNB at a downlink subframe i, the PHICH corresponds tothe PUSCH that the UE transmits at an uplink subframe i−k. At this time,the k value is shown in Table 20.

Table 20 shows a transmission timing relationship of the PUSCH and thePHICH corresponding to the PUSCH according to uplink-downlinkconfigurations.

TABLE 20 TDD UL/DL Config- subframe number i uration 0 1 2 3 4 5 6 7 8 90 7 4 7 4 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 6 4 7 4 6

In the of uplink-downlink configurations 1 to 6 or in the case ofuplink-downlink configuration 0 and I_(PHICH)=0, if the UE receives thePHICH transmitting a HARQ-ACK signal from the eNB at a subframe i, thePHICH corresponds to the PUSCH that the UE transmits at a subframe i−k.On the other hand, in the uplink-downlink configuration 0 andI_(PHICH)=1, if the UE receives the PHICH transmitting the HARQ-ACKsignal from the eNB at the subframe i, the PHICH corresponds to thePUSCH that the UE transmits at a subframe i−6.

If the UE transmits a transport block to the eNB through the PUSCHsubframe corresponding to a downlink subframe i and receives the PHICHcorresponding to the transport block from the downlink subframe i; andthe received PHICH is decoded as ACK or the transport block is disabledby the PDCCH transmitted from the downlink subframe i, the UE transmitsthe ACK corresponding to the transport block to an upper layer.Otherwise, the UE transmits NACK with respect to the transport block tothe upper layer.

From the viewpoint of the UE, the ACK/NACK response (or PHICH) withrespect to the uplink transmission through the PUSCH of the UE at then-th uplink subframe is transmitted to the eNB according to thecorresponding uplink subframe index at the (n+k)-th downlink subframewhich corresponds to the uplink subframe index. In the case of subframebundling, the corresponding PHICH corresponds to the last subframe ofthe bundle. The UE should be able to predict that the eNB will transmitat the (n+k)-th downlink subframe a PHICH response with respect to thePUSCH that the UE has transmitted and has to searchfor/detect/demodulate the corresponding PHICH accordingly. At this time,the k value follows as shown in Table 21.

Table 21 shows a transmission timing relationship of the PUSCH and thePHICH corresponding to the PUSCH according to uplink-downlinkconfigurations.

TABLE 21 TDD UL/DL Config- subframe index n uration 0 1 2 3 4 5 6 7 8 90 4 7 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 4 6 6 4 7

The PHICH resources are identified by an index pair such as (n_(PHICH)^(group),n_(PHICH) ^(seq)). n_(PHICH) ^(group) represents the PHICHgroup number; and n_(PHICH) ^(seq) represents an orthogonal sequenceindex within the corresponding PHICH group. n_(PHICH) ^(group) andn_(PHICH) ^(seq) can be obtained by Eq. 11 as follows.

n _(PHICH) ^(group)+(I _(PRB) _(_) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(_) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH).  [Eq. 11]

where n_(DMRS) is mapped from the cyclic shift for the DMRS fieldthrough the most recent PDCCH having the uplink DCI format intended fora transport block related to the transmission of the correspondingPUSCH. On the other hand, in the case of absence of the PDCCH having theuplink DCI format for the same transport block, the initial PUSCH forthe same transport block is scheduled semi-persistently or n_(DMRS) isset to 0 if the initial PUSCH is scheduled by a random access responseapproval signal.

N_(SF) ^(PHICH) represents the size of a spreading factor used for PHICHmodulation.

I_(PRB) _(_) _(RA) gives the same index as I_(PRB) _(_) _(RA) ^(lowest)^(_) ^(index) when I_(PRB) _(_) _(RA) indicates the first transportblock of the PUSCH related to the PDCCH, or when there is no relatedPDCCH and the number of transport blocks specified manually is not thesame as the number of transport blocks specified by the most recentPDCCH related to the corresponding PUSCH. On the other hand, in caseI_(PRB) _(_) _(RA) indicates the second transport block of the PUSCHrelated to the PDCCH, I_(PRB) _(_) _(RA) returns the same index as theI_(PRB) _(_) _(RA) ^(lowest) ^(_) ^(index)+1. At this time, I_(PRB) _(_)_(RA) ^(lowest) ^(_) ^(index) corresponds to the lowest PRB index of thefirst slot for the transmission of the corresponding PUSCH.

N_(PHICH) ^(group) represents the number of a PHICH group formed by anupper layer.

I_(PHICH) is 1 if the UE transmits the PUSCH at the subframe index 4 or9 for the case of uplink-downlink configuration 0 of the TDD system;otherwise, 0.

Table 22 shows a mapping relationship between the cyclic shift for theDMRS field used for determining the PHICH resources through the PDCCHhaving the uplink DCI format and n_(DMRS).

TABLE 22 Cyclic Shift for DMRS Field in PDCCH with uplink DCI formatn_(DMRS) 000 0 001 1 010 2 011 3 100 4 101 5 110 6 111 7

In what follows, to described a method for minimizing control planelatency of a UE in the 5G system (or future IMT-advanced system),technical details related to a definition of a contention-based PUSCHzone (hereinafter, it is called a ‘CP zone’), a method for setting a CPzone, and a method for using a CP zone will be given with reference torelated drawings.

Definition and Configuration of CP Zone

FIG. 25a shows one example of configuring a CP zone, and FIG. 25billustrates one example of a contention PUSCH resource block (CPRB)constituting a CP zone.

First, a CP zone refers to a region where the UE can transmit UL datadirectly without scheduling of resource allocation from the eNB withrespect to transmission of uplink data of the UE.

The CP zone can be used primarily for the UE to transmit UL datarequiring low latency.

With reference to FIG. 25a , 1010 corresponds to a resource region towhich the PUCCH is transmitted, and 1020 corresponds to the CP zone.

The CP zone can be allocated to a particular resource area within thePUSCH region to which the UL data can be transmitted. In other words,the CP zone can be allocated to one subframe or one or more consecutivesubframes, and the CP zone may not be allocated to a particularsubframe.

FIG. 25b represents a CPRB, and a CP zone can consist of one or moreCPRBs.

A CPRB represents a resource region that a UE can occupy within a CPzone. One CPRB 1030 is mapped to one UE, but a plurality of CPRBs can bemapped to one UE based on capability of the UE, the amount of UL datathat the UE transmits, and so on. Similarly, a plurality of UEs mayshare one CPRB.

As shown in FIG. 25b , N (where N is a natural number) CPRBs can bedefined within a CP zone.

As one example, suppose 3 UEs (UE 1, UE 2, UE 3) share one CP zone and 4CPRBs (CPRB #1, CPRB #2, CPRB #3, CPRB #4) comprise the CP zone. In thiscase, CPRB #1 can be allocated to the UE 1; CPRB #2 to the UE 2; andCPRB #3 to the UE 3.

At this time, the eNB may configure the CPRBs to be allocated to therespective UEs. In case the UEs receive CPRB-related information of a CPzone from the eNB, each UE may request the eNB to allocate the CPRBdesired by the UE.

Also, in the case of a small cell where the number of UEs (or users)that a cell can accommodate is limited, the eNB may map the CPRB 1-to-1to the UE when the CPRBs are allocated to the respective UEs.

For example, in case the maximum number of UEs that a small cell canaccommodate is N, the eNB of the small cell pre-allocates a CP zone forthe N UEs and prevents those UEs beyond the predetermined number N fromentering the cell so that the CPRBs can be mapped 1-to-1 to the UEswithin the cell.

If the RACH procedure employs the 1-to-1 mapping between the UEs and theCPRBs after a UE enters a cell, a CPRB allocation method is decidedimplicitly between the UE and the eNB before the UE enters the cell. Inother words, in case the UE connected to a macro cell adds a connectionto a small cell through dual connectivity, the CPRBs can be allocatedbeforehand to the UE through a backhaul interface between the small celland the macro cell.

At this time, dual connectivity refers to the technology such asanchor-booster, carrier aggregation, and simultaneous multi-RATcommunication.

In other words, a UE located within a cell having a CP zone can transmitUL data that require low latency transmission directly to the eNBthrough the CP zone without using the eNB's scheduling (without an ULgrant) for transmission of the UL data.

When it comes to the UE's transmission of UL data that requires lowlatency, it is preferable to use a CP zone for wide applications;however, a CP zone may be used restrictively only for the UL data (asone example, an RRC request message and/or a NAS request message in arandom access procedure, BSR transmission in a BSR procedure, and so on)transmitted within a particular procedure.

As shown in FIG. 26, a CP zone may be set up differently according toindividual procedures.

A CP zone can be defined to consist of one or more zones depending onits objective. For example, a CP zone area defined for the RACHprocedure can be different from the CP zone area defined for the BSRprocedure. In other words, CP zones defined on the basis of differentobjectives can be formed in the respective subframes different from eachother or can be formed on different resource blocks within the samesubframe.

FIG. 26 illustrates that a CP zone meant for the RACH procedure is setdifferently from the CP zone intended for a different procedure such asthe BSR procedure.

Method for Transmitting CP Zone-Related Information

FIG. 27 illustrates one example of a method for transmitting informationrelated to a CP zone.

If a CP zone is set up in a particular cell, the eNB (or a particularcell) transmits control information related to a CP zone formed in theparticular cell to the UEs (within the particular cell) S2710.

At this time, the particular cell may refer to a small cell such as afemto cell, pico cell, and micro cell; or a macro cell.

The CP zone-related control information includes CP zone set-upnotification information indicating whether a CP zone has been formedfor the particular cell.

If a CP zone is formed in the particular cell, the CP zone-relatedcontrol information further includes CP zone set-up information which isrelated to the information related to setting up the CP zone, such asconfiguration of the CP zone.

The CP zone set-up information can information about uplink resources inwhich the CP zone is set up and information related to data transmissionthat can be transmitted to a CPRB within the CP zone.

The information about uplink resources in which the CP zone is set upmay include information of an UL subframe which does not have a CP zoneby taking into account resource utilization.

As described above, one CP zone can consist of N (which is a naturalnumber) CPRBs that are occupied by one or more UEs.

The information about uplink resources in which the CP zone is set upcan include a value indicating the number (M) of CP zones that anarbitrary UE can attempt to occupy at a particular time point.

At this time, N*M represents the total number of CPRBs that an arbitraryUE can select (or occupy) at a particular time point.

For example, if a CP zone has 4 CPRBs and there are 2 CP zones with thesame objective (two CP zones form a CP group), a UE can have a total of8 (4*2) candidate CPRBs.

The information related to data transmission that can be transmitted tothe CPRB can include maximum resource block size for each UE, modulationand coding scheme (MCS) level, initial transmission power reference, andso on.

The CP zone-related control information can be transmitted through abroadcast message or through a unicast message intended for a particularUE.

More specifically, the CP zone-related information can be transmitted infour different ways as shown below; however, it should be noted that thepresent invention is not limited to the descriptions below butaccommodates various other transmission methods.

First, CP zone-related control information can be transmitted to the UEthrough a master information block (MIB). The CP zone related controlinformation can be included in the MIB which transmits essentialphysical layer information.

Second, CP zone-related control information can be transmitted to the UEthrough an existing SIB-x.

Transmission through SIB-x corresponds to the case where a CP zone isset up for initial network connection; thus, the CP zone-related controlinformation can be transmitted being included in SIB-2.

As one example, in case a CP zone is set up for the RACH procedure,information about the CP zone is added to the SIB-2 to make the UEinformed through transmission of a contention based RRC connectionrequest message (for example, 2-step RA) before the UE is connected to acell that the UE can connect to the cell.

Third, CP zone-related control information can be transmitted to the UEthrough a new SIB-y.

In other words, in case a CP zone is set up for a procedure afternetwork connection, the CP zone-related control information can betransmitted by defining a new SIB.

At this time, the eNB can transmit information indicating that a cellhas to receive new SIB information to the UE by including theinformation in the MIB, SIB-1, or SIB-2.

Fourth, CP zone-related control information can be transmitted to aparticular UE through a new control message according to a unicastscheme.

In case the UE is connected to a cell, the CP zone-related controlinformation is transmitted through a unicast message only to the UE thatneeds to use a CP zone so that only the particular UE can receive the CPzone-related control information.

In case the UE connects (or enters) to the cell, the UE transmitsinformation about an intent to use a CP zone to the eNB by including theinformation in a message which is transmitted to the eNB at the time ofthe UE's connecting to the cell. Thus, the UE can make the eNB transmitCP zone-related control information to the UE through a unicast message.

As described above, the CP zone set-up notification information and theCP zone set-up information may be transmitted to UEs through variousforms (SIB, MIB, unicast message, and so on) being included in the CPzone-related control information. Or the CP zone notificationinformation and the CP zone set-up information can be transmittedseparately through different messages from each other.

At this time, it should be noted that even if the CP zone set-upnotification information and the CP zone set-up information aretransmitted separately, they can be transmitted through various formssuch as the SIB, MIB, unicast message, and so described above.

CP Zone-Based BSR Procedure

In the following, a method for using a CP zone in a BSR procedure willbe described in more detail.

FIG. 28 illustrates one example of a method for using a CP zone in abuffer state report (BSR) procedure.

A BSR procedure is an UL resource allocation procedure and can berepresented as a scheduling request (SR) procedure.

FIG. 28 shows a method for using a contention-based PUSCH (CP) zone asan UL resource for a BSR message transmission.

As shown in FIG. 28, a BSR is transmitted together with an SR from asubframe which transmits the SR. In other words, the UE transmits theBSR together with the SR to the eNB at 1 TTI (Transmission TimingInterval) S2810.

At this time, it is assumed that transmission of the SR is carried outthrough the PUCCH according to the ON/OFF keying scheme and PUCCHresources are pre-allocated to each UE.

Also, the UE can employ an SR carrying particular information for asystem which uses a 5-step SR method of FIG. 18a and a 3-step SR methodof FIG. 18b simultaneously.

As one example, the particular information may denote a non-contentionbased SR in the case of ‘0’ and a contention-based SR in the case of‘1’.

More specifically, the UE transmits an SR through the PUCCH and a BSRthrough a CP zone together to the eNB at 1 TTI, namely, at the samesubframe S2820.

Afterwards, the UE receives an UL grant for transmission of actual datafrom the eNB.

Then the UE transmits actual data to the eNB by using the received ULgrant S2830.

At this time, in order to carry out an UL resource allocation process byusing a CP zone, the eNB can first of all transmit the CP zone-relatedcontrol information.

Since the CP zone-related control information is system-relatedinformation, it is preferable to transmit the CP zone-related controlinformation through an SIB, but the CP zone-related control informationcan be transmitted in various ways, not being limited to the case above.

As described above, in case an UL resource allocation process is carriedout by using a CP zone, the UE can request UL resources from the eNB andreduce a time period during which to receive the UL resources from theeNB, thereby reducing the overall procedure latency compared with the ULresource allocation procedure based on normal scheduling by the eNB.

FIGS. 29a to 29c illustrate one example of setting up a CP zone invarious ways in case the BSR procedure employs the CP zone.

In case a BSR message is transmitted through a CP zone, the UE cantransmit a BSR message along with an SR through the PUCCH resourcesallocated to the UE.

By doing so, the UE can transmit the SR and the BSR message together byusing the resources at the same time point or across consecutive timeframes.

FIG. 29a shows one example of a method for setting up an intra-subframeof a CP zone where the SR and the BSR message are transmitted within thesame subframe.

In other words, as shown in FIG. 29a , the SR and the BSR message areallocated (TDM/FDM) being assigned to different resources (time domainresources or frequency domain resources) within the same subframe.

FIG. 29b shows one example of a method for setting up an inter-subframeof a CP zone where the SR and the BSR message are transmitted within aneighboring subframe.

In other words, as shown in FIG. 29b , the SR and the BSR message may beallocated being assigned to different TTIs through resources of aneighboring subframe.

The BSR message can be transmitted at the next subframe after SRtransmission or at the N-th subframe after SR transmission.

FIG. 29c shows one example of a method for setting up a CP zone bycombining the methods of FIGS. 29a and 29 b.

In other words, to maximize resource utilization within a cell, thecompound method of the intra subframe and the inter subframe methods ofFIG. 29c does not set up an SR region or a CP zone resource region in aparticular subframe.

With reference to FIG. 29c , an SR is allocated to one subframe, and anSR and a CP zone resource region are allocated together in the nextsubframe.

At this time, the SR and the CP zone resource region are allocated byusing frequency resources different for each other.

In addition to the methods of FIGS. 29a to 29c , a method for setting upan SR region and a method for setting up a resource region of a CP zonecan be determined in various ways according to cell-operatingtechniques.

In what follows, a method for CPRB mapping in a BSR procedure accordingto an SR PUCCH index will be described.

FIG. 30 illustrates one example of a method for CPRB mapping in a BSRprocedure.

FIG. 30 illustrates one example of a method for setting up an SR and aCPRB to be 1-to-1 mapped to each other.

In other words, in case n SRs are allocated in one subframe, the methodof FIG. 30 set up a CP zone having n CPRBs.

Two methods can be used for setting up an SR and a CPRB to be mapped1-to-1 to each other.

(1) A method for selecting a CPRB index in the same manner as done forthe PUCCH physical index with respect to an SR.

(2) A method for selecting a CPRB index in the same manner as done forthe PUCCH logical index with respect to an SR.

In the second method (2), the PUCCH logical index with respect to an SRdenotes a new index obtained by mapping the PUCCH resource indexallocated for the SR of the UEs in the corresponding subframe logicallystarting from 0.

The PUCCH logical index can be transmitted after being newly defined byan SR configuration information element.

FIG. 30a illustrates a method for mapping an SR and a CPRB 1-to-1 toeach other in a method for setting up an inter-subframe of a CP zone;and FIG. 30b illustrates a method for mapping an SR and a CPRB 1-to-1 toeach other in a method for setting up an intra-subframe of a CP zone.

With reference to FIG. 30a , in case the UE 1 transmits an SR to the eNBthrough the PUCCH index 3 at a subframe n, the UE 1 transmits a BSRmessage to the eNB in the next subframe, namely, in the subframe (n+1)by using the CPRB index 3 (#3) which is the same as the PUCCH index 3.

Also, in case the UE 2 transmits an SR to the eNB through the PUCCHindex 3 at a subframe (n+2), the UE 2 transmits a BSR message to the eNBin the next subframe, namely, in the subframe (n+3) by using the CPRBindex 3 (#3) which is the same as the PUCCH index 3.

With reference to FIG. 30b , in case the UE 1 transmits an SR to the eNBthrough the PUCCH index 0 at a subframe n, the UE 1 transmits a BSRmessage to the eNB in the same subframe n by using the CPRB index 0 (#0)which is the same as the PUCCH index 0.

Also, in case the UE 2 transmits an SR to the eNB through the PUCCHindex 3 at a subframe n, the UE 2 transmits a BSR message to the eNB inthe same subframe n by using the CPRB index 3 (#3) which is the same asthe PUCCH index 3.

In the following, another method for mapping between an SR and a BSRCPRB will be described.

In this method, the number of CPRBs is set to be smaller than the numberof resources for an SR. In other words, in case n SRs are allocated forone subframe, this method sets up a CP zone with 1 to n−1 CPRBs.

In this case, since the number (x) of CPRBs is smaller than the number(n) of

SRs, there can be a chance for BSR transmission collision.

Therefore, to reduce collision during BSR transmission, the followingmethods are used so that the UE can implicitly select a CPRS for a BSRmessage.

(1) A method for a UE to select a CPRB in a random fashion.

(2) A method for a UE to select a CPRB by CPRB index(#)=modulo(UE ID %X).

(3) A method for a UE to select a CPRB by CPRB index(#)=modulo(PUCCHphysical index with respect to an SR % X).

At this time, the PUCCH physical index can denote a value correspondingto the PUCCH resource index among SR configuration information elements.

(4) A method for a UE to select a CPRB by CPRB index(#)=modulo(PUCCHlogical index with respect to an SR % X).

At this time, the PUCCH logical index denotes a new index obtained bymapping the PUCCH resource index allocated for the SR of the UEs in thecorresponding subframe logically starting from 0; the correspondingPUCCH logical index can be transmitted additionally for the UE from anSR configuration information element.

In the method of (2), in case X is set by the value which is not adivisor of n, a particular CPRB is selected much more than others by theUEs; thus, the chances of collision can be further increased.

Therefore, due to this reason, it may be preferable to set X as adivisor of n, but the present invention is not limited to this case.

As one example, in case n=6, it may be preferable to set X to one fromamong 1, 2, 3, and 6.

In the methods of (2) to (4), X denotes a total number of CPRBs that areoccupied by the UE transmitting a BSR message. Also, the X valuecorresponds to the value received from the eNB through systeminformation.

Given that the number of SRs allocated to an arbitrary subframe PUCCH isn, if the number of CPRBs for BSR transmission corresponding thereto isn or more, the UE does not collide with other UEs at the time oftransmitting a BSR message to a CPRB.

However, as described above, if the number of CPRBs corresponding (orbeing mapped) to n SRs is set to n−1 or less, there can be chances thatone or more UEs transmit a BSR message to the eNB at the same timethrough the same CPRB.

FIG. 31 illustrates one example of collision occurred at the time of BSRtransmission due to occupation of the same CPRB.

In the case of FIG. 31, the index (CPRB(#)) of a CPRB that the UEselects can be calculated as modulo (selected SR PUCCH index % X), andFIG. 31 shows the case where X=5.

X denotes a total number of CPRBs that are occupied by the UEtransmitting a BSR message. And the X value corresponds to the valuereceived from the eNB through system information.

As shown in FIG. 31, the UE 1 transmits an SR to the eNB through thePUCCH resources corresponding to the PUCCH index 1 and a BSR message tothe eNB through the CPRB corresponding to the CPRB #1.

Also, the UE 2 transmits an SR to the eNB through the PUCCH resourcescorresponding to the PUCCH index 2 and a BSR message to the eNB throughthe CPRB corresponding to the CPRB #1.

In other words, as the UE 1 and the UE 2 transmit a BSR message to theeNB through the same CPRB, resource collision is occurred in the eNB,where the enB is unable to distinguish BSR messages sent from the UE 1and the UE 2.

In what follows, described will be a method for recognizing collisionbetween BSR messages and a method for resolving collision in case two ormore UEs transmit a BSR message by using the same CPRB resources.

In other words, in the case of collision as two or more UEs transmit aBSR message by using the same CPRB resources, the eNB recognizes theoccurrence of collision due to transmission of BSR messages, commandsthe corresponding UEs to re-transmit the BSR messages, and transmits aBSR UL grant to notify that the corresponding UL grant is resourceallocation to request re-transmission of BSR messages.

In other words, once the eNB successfully receives a BSR message of theUE through a CPRB, the eNB transmits an UL grant with respect to actualdata to the UE without indication.

However, in case the eNB fails to receive a BSR message though it hasreceives an SR from two or more UEs through the PUCCH, the eNB transmitsan UL grant for the BSR message to the UEs together with BSR UL grantindication which notifies that the corresponding UL grant is intendedfor BSR transmission.

In what follows, a method for relieving collision due to UEs' occupyingthe same CPRB will be described in more detail.

In other words, in case UEs transmit the UL data by using the CP zone,described with reference to FIGS. 32 to 34 will be a method for relivingcollision during UL data transmission that can occur as the UEs selectthe same CPRB and collision due to transmission and reception of HARQACK/NACK signals during the UL data transmission.

First, described briefly are a method for UL data transmission based onthe multi-user (MU)-MIMO scheme and a method for transmitting andreceiving an error correction response (HARQ ACK/NACK) defined in theLTE-A system.

In the current version of the LTE-A system, UL data are transmitted onthe basis of scheduling of an eNB; therefore, the eNB can know which UEwill transmit the UL data through which resources.

In other words, the eNB regards the data transmitted through the PUSCHresources mapped to the UL grant of the PUCCH that the eNB has specified(or allocated) as the UL data transmitted by the UE which has receivedthe corresponding UL grant.

In case the UE transmits UL data to the eNB by using the MU-MIMO scheme,two or more UEs can transmit disparate data to the eNB by using the sametime and/or frequency resources.

At this time, in order to receive the disparate UL data transmittedthrough the same resources by the UEs, the eNB allocates a DMRSseparately for each UE to receive individual channel information of theUL data transmitted by the UEs and successfully decodes the UL datatransmitted by the respective UEs.

Also, the eNB transmits the HARQ ACK/NACK about the UL data successfullyreceived from the UEs to the respective UEs through the PHICH resourcesmapped to the PUSCH resources scheduled by the eNB.

The eNB allocates cyclic shifts meant for individual DMRSs to two ormore UEs having the same lowest PRB index; thus, the corresponding UEsare enabled to transmit ACK/NACK signals by using different PHICHresources.

In case radio channel states among two or more UEs (for example, H₀, H₁,. . . , H_(n)) are not orthogonal to each other, the eNB may not be ableto properly receive the UL data that the UEs transmit through the sameresources.

However, if radio channel states among two or more UEs (for example, H₀,H₁, . . . , H_(n)) are orthogonal to each other, the eNB cansuccessfully receive the UL data transmitted from the two or more UEseven though the UL data are transmitted through the same resources bythe two or more UEs.

In case UL data are transmitted through a contention-based PUSCH zone(CP zone), in other words, in case multi-users (a plurality of UEs)transmit uplink data without an UL grant from the eNB, currently nomethod is defined for providing the eNB with information (for example,DMRS for individual UL data) with which to successfully decode multi-ULdata of the UEs transmitted through the same CPRB resources.

Also, even if the eNB successfully receives disparate UL data ofindividual UEs transmitted through the same CPRB resources, since nomethod is defined for providing resource information of an errorcorrection response (HARQ ACK/NACK) with respect to the UL data ofindividual UEs, currently UEs are unable to check errors during UL datatransmission.

Therefore, in what follows, a method for transmitting and receiving ULdata successfully by using the same CPRB resources of a CP zone and amethod for transmitting and receiving the HARQ ACK/NACK signal accordingto the present invention will be described.

For successful transmission and reception of UL data transmitted withoutan UL grant (the UL data transmitted through a CP zone), the presentinvention provides a method for setting a cyclic shift value accordingto particular methods and using the cyclic shift value for setting upCPRB/DMRS and resources (for example, PHICH) for error correctionresponses (HARQ ACK/NACK).

FIG. 32 illustrates one example of a method for setting a DMRS cyclicshift of a CPRB according to the present invention.

In case UL data are transmitted directly through a CP zone withoutreceiving an UL grant from the eNB, the UE is unable to receive a DMRSCS value transmitted through the UL grant. Thus, the present inventionprovides a method for setting a DMRS CS based on CPRB indicationinformation, as shown in FIG. 32.

In other words, as shown in FIG. 32, the UE is unable to receive a DMRSCS value since the UE transmits UL data through a CP zone, where theDMRS CS value is used with respect to the CPRBs selected according to apredetermined rule. Now, the UE maps the DMRS CS value according to CPRBindication information (for example, CPRB indicator) so that resourcecollision among UEs selecting the same CPRB resources can be avoided.

At this time, resource collision refers to the concept including bothresource collision among disparate data transmitted through the sameresources and collision of resources for an error correction response(PHICH) in response to the aforementioned resource collision.

The CPRB indication information refers to a signal transmitted throughthe PUSCH or the PUCCH or a sequence and can be used as an identifierfor identifying a particular UE and/or data transmitted through the same(or consecutive) subframe(s) with the CPRBs.

In other words, the CPRB indication information can be (1) a randomlyselected preamble sequence of the RACH procedure, (2) a pre-allocatedpreamble sequence at the time of handover (HO), (3) particular resourceindex (physical index or logical index) with respect to the PUCCH SR atthe time of transmission of an SR, (4) a particular sequence usingresources newly defined for an CPRB, an index, or a code value.

Also, the CPRB indication information can be represented in the form ofa CPRB indicator.

From now on, the CPRB indication information will be described in moredetail.

As shown in FIG. 32, UE 1 and UE 2 transmit UL data to the eNB through aCPRB along with CPRB indication information S3210.

The UE 1 and the UE 2 use different CPRB indication information fromeach other and select the same CPRB.

DMRS CS values different from each other are allocated implicitly to therespective UEs according to a predetermined rule on the basis of theCPRB indication information.

In other words, each UE and the eNB are now enabled to implicitlycalculate different DMRS CS values according to a predetermined rulebased on the CPRB indication information.

Through the operation above, the eNB can identify the UL data of the UE1 from the UL data of the UE 2, all of which are transmitted through thesame CPRB and allocate different PHICH resources to the UL data of therespective UEs.

The method for allocating different DMRS CSs according to apredetermined rule will be described in more detail with reference toFIGS. 33 and 34.

The eNB allocates different DMRS CSs to the UE 1 and the UE 2, therebyallocating different PHICH resources to the respective UEs. And the eNBtransmits to each UE the HARQ ACK/NACK with respect to UL datatransmission performed by the corresponding UL through the allocatedPHICH resources S3220.

FIG. 33 illustrates one example of a method for setting a DMRS cyclicshift value according to the present invention.

In case UL data are transmitted through a CP zone, a method forpreventing collision during transmission of UL data through the sameCPRB resources and a method for mapping DMRS CS values used fortransmission of HARQ ACK/NACK signals may be employed; and the UE andthe eNB can implicitly calculate the DMRS CS values through the methods.

In other words, the CS value assigned to a particular UE can becalculated by the following Eq. 12.

CS for a UE=[(CPRB indicator value−CPRB index)/N],  [Eq. 12]

where N represents a total number of CPRBs within a CP zone, and CPRBindex corresponds to CPRB indication information (CPRB indicator)divided by N (CPRB indicator value % N), having an integer value suchthat 0≦CPRB index<N.

In the LTE-A system, the CS value mapped to the DMRS is an integerbelonging to the range of 0≦CS≦7 and can take a total of 8 values.

In other words, through the Eq. 12, with respect to the same CPRBselected by different UEs, different CS values as many as 0<(the maximumvalue of the CPRB indicator+1)/N>−1 can be set up.

For example, if the maximum value of the CPRB indicator value is 9 and Nis 4, different cyclic shift values ranging from 0 to 2 are set upaccording to Eq. 12.

At this time, 2 is calculated from the equation, 2=<(9+1)/4>−1, and < >stands for a rounded up value, where, for example, <2.5> returns 3.

As shown in FIG. 33, suppose the CPRB indicator values are given by 0,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and a total number ofCPRBs within a CP zone (N) is 4. Then the CPRB index is set up as 0, 1,2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3 (which is obtained as theremainder of the CPRB indicator divided by N).

Therefore, the CS determined according to Eq. 12 has the value of 0, 0,0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3.

At this time, it is assumed that different values are assigned to theCPRB indicator values for the respective UEs.

As described above, even if the UEs have the same CPRB index (the UEhaving a CPRB indicator value of 0 and the UE having a CPRB indicatorvalue of 4 have the same CPRB index of 0), different cyclic shift valuesare allocated to the individual UEs according to Eq. 12. Therefore,collision due to transmission of UL data through the same CPRB can beavoided, and accordingly, the HARQ ACK/NACK with respect to the UL datatransmitted by the UEs can be transmitted separately to the respectiveUEs.

In other words, in case the UEs select CPRB indicator values alldifferent from each other, the UEs select particular CPRBs individuallyby receiving from the eNB CPRB indicator values all different from eachother, or the UEs set up DMRS CS values with respect to CPRBs throughEq. 12, a total of 8N (which corresponds to the case where a maximumnumber of CS values is 8) data can be transmitted orthogonally through NCPRBs.

At this time, the (ideally) maximum number of UL data that can betransmitted orthogonally according to the number of CS values (NCS) canbe determined as NCS*N.

If the maximum number of CS values is 8 and the CPRB indicator has arange larger than 8N, there are chances for collision duringtransmission of UL data performed by two or more UEs and collisionduring transmission and reception of error correction responses since,as shown in FIG. 33, the same cyclic shift value can be set up accordingto the same CPRB even if different CPRB indicator values are set to twoor more UEs. Therefore, it is preferable that the range of the CPRBindicator value is restricted not to have a value larger than 8N.

FIG. 34 illustrates another example of a method for setting a DMRScyclic shift value according to the present invention.

FIG. 34 illustrates the case where a CS values is determined simply onthe basis of a CPRB indicator value. Different from FIG. 33, the methodof FIG. 34 is preferable for the case where the CPRG indicator value isnot used for setting up the CPRB index.

In other words, the DMRS CS value allocated with respect to a particularUE can be calculated through the following Eq. 13.

CS for a UE=CPRB indicator value % NCS,  [Eq. 13]

where NCS represents the maximum value of the CS+1, namely, a totalnumber of CS values.

As one example, in the LTE-A system, the CS value ranges from 0 to 7;thus, NCS becomes 8.

As shown in FIG. 34, suppose the CPRB indicator values are given by 0,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and NCS value is 8.Then the DMRS CS value with respect to the CPRB becomes 0, 1, 2, 3, 4,5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, respectively.

In the case of a method for setting up a DMRS CS value with respect to aCPRB through a method of FIG. 34, the number of CSs used is increasedaccording to the number of UEs; therefore, the usage for radio resourcesin the LTE-A system can be increased accordingly.

As a yet another embodiment, the DMRS CS value with respect to the CPRBmay be set up through a UE ID.

In other words, by setting up a DMRS CS with respect to a CPRB by usinga CPRB indicator value and a UE ID, resource collision (collision of ULdata transmission and collision of HARQ ACK/NACK signals) due toselection of the same CPRB can be prevented.

Overview of an Apparatus to which the Present Invention can be Applied

FIG. 35 illustrates a block diagram of a wireless communication deviceto which the present invention can be applied.

With reference to FIG. 35, a wireless communication system comprises aneNB 3510 and a plurality of UEs 3520 located within the coverage of theeNB 3510.

An eNB 3510 comprises a processor 3511, a memory 3512, and a radiofrequency (RF) unit 3513. The processor 3511 implements a function,process and/or method propose through FIGS. 1 to 34. Layers of radiointerface protocols can be implemented by the processor 3511. The memory3512, being connected to the processor 3511, stores various types ofinformation to operate the processor 3511. The RF unit 3513, beingconnected to the processor 3511, transmits and/or receives a radiosignal.

A UE 3520 comprises a processor 3521, a memory 3522, and a radiofrequency (RF) unit 3523. The processor 3521 implements a function,process and/or method propose through FIGS. 1 to 34. Layers of radiointerface protocols can be implemented by the processor 3521. The memory3522, being connected to the processor 3521, stores various types ofinformation to operate the processor 3521. The RF unit 3523, beingconnected to the processor 3521, transmits and/or receives a radiosignal.

The memory 3512, 3522 can be located inside or outside the processor3511, 3512 and can be connected to the processor 3511, 3521 through awell-known means.

The eNB 3510 and/or the UE 3520 can have a single antenna or multipleantennas.

The embodiments described above are a combination of constitutingelements and features of the present invention in particular forms.Unless otherwise specified, each constituting element or feature shouldbe regarded to be selective. Each constituting element or feature can beembodied solely without being combined with other constituting elementor feature. It is also possible to construct embodiments of the presentinvention by combining part of constituting elements and/or features.The order of operations illustrated in the embodiments of the presentinvention can be changed. Part of a structure or feature of anembodiment can be included by another embodiment or replaced with thecorresponding structure or feature of another embodiment. It should beclear that embodiments can also be constructed by combining those claimsrevealing no explicit reference relationship with one another, or thecombination can be included as a new claim in a revised application ofthe present invention afterwards.

Embodiments according to the present invention can be realized byvarious means, for example, hardware, firmware, software, or acombination thereof. In the case of hardware implementation, theembodiments of the present invention can be implemented by one or moreof ASICs (Application Specific Integrated Circuits), DSPs (DigitalSignal Processors), DSPDs (Digital Signal Processing Devices), PLDs(Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays),processors, controllers, microcontrollers, microprocessors, and thelike.

In the case of firmware or software implementation, methods according tothe embodiment of the present invention can be implemented in the formof a module, procedure, or function carrying out operations describedabove. Software codes can be stored in a memory unit and executed by aprocessor. The memory unit, being located inside or outside theprocessor, can communicate data with the processor through various meansknown in the fields of the art.

It should be clearly understood by those skilled in the art that thepresent invention can be realized in a different, particular form aslong as the present invention retains the essential features of thepresent invention. Therefore, the detailed description above should notbe interpreted limitedly from all aspects of the invention but should beregarded as an illustration. The technical scope of the invention shouldbe determined through a reasonable interpretation of the appendedclaims; all the possible modifications of the present invention withinan equivalent scope of the present invention should be understood tobelong to the technical scope of the present invention.

INDUSTRIAL APPLICABILITY

This document discloses a method for requesting scheduling for uplinkdata transmission in a wireless communication system with examples basedon the 3GPP LTE/LTE-A system; however, the present invention can beapplied to various other types of wireless communication systems inaddition to the 3GPP LTE/LTE-A system.

1. A method for transmitting uplink (UL) data requiring low latency in awireless communication system, the method performed by a UE (userequipment), comprising: transmitting contention PUSCH resource block(CPRB) indication information used for identifying a particular UEand/or particular data to an eNB; transmitting UL data to the eNBthrough CPRB resources of a contention based PUSCH (CP) zone; andreceiving a hybrid automatic retransmit request (HARQ) response withrespect to the UL data from the eNB through a physical hybrid ARQindicator channel (PHICH), wherein the CP zone is a resource area fromwhich UL data are transmitted without allocation of an UL grant andwherein the CPRB resource and the PHICH is mapped to a cyclic shift (CS)set up based on the CPRB indication information.
 2. The method of claim1, wherein the CPRB indication information is a signal or a sequencetransmitted through a physical uplink shared channel (PUSCH) or aphysical uplink control channel (PUCCH).
 3. The method of claim 2,wherein the cyclic shift value is determined through the followingequation:${{CS}\mspace{14mu} {value}} = {\left\lbrack \frac{{{CPRB}\mspace{14mu} {indication}\mspace{14mu} {information}\mspace{14mu} {value}} - {{CPRB}\mspace{14mu} {index}}}{A\mspace{14mu} {total}\mspace{14mu} {number}\mspace{14mu} {of}\mspace{14mu} {{CPRBs}(N)}} \right\rbrack.}$4. The method of claim 3, wherein the CPRB index is given by a remainderof a CPRB indication information value divided by N.
 5. The method ofclaim 3, wherein the value of a cyclic shift ranges from 0 to <(themaximum value of the CPRB indication information value+1)/N>−1 for thesame CPRB.
 6. The method of claim 2, wherein the cyclic shift value isdetermined through the following equation:CS value=CPRB indication information % the number of CS values.
 7. Themethod of claim 1, wherein the PHICH is assigned for each UE accordingto the cyclic shift value.
 8. The method of claim 1, wherein the CPRBindication information and the UL data are transmitted from the samesubframe or through consecutive subframes.
 9. A method for receiving ULdata requiring low latency in a wireless communication system, themethod performed by an eNB, comprising: receiving contention PUSCHresource block (CPRB) indication information used for identifying aparticular UE and/or particular data from at least two or more UEs;receiving uplink (UL) data through CPRB resource of a contention basedPUSCH (CP) zone from the at least two or more UEs; and transmitting ahybrid automatic retransmit request (HARQ) response with respect to theUL data through a physical hybrid ARQ indicator channel (PHICH) to theat least two or more UEs, wherein the CP zone is a resource area fromwhich UL data are transmitted without allocation of an UL grant andwherein the CPRB resource and the PHICH is mapped to a cyclic shift (CS)set up based on the CPRB indication information.
 10. A user equipmentfor transmitting uplink (UL) data in a wireless communication system,comprising: a radio frequency (RF) unit for transmitting and receiving aradio signal; and a processor, wherein the processor is controlled totransmit contention PUSCH resource block (CPRB) indication informationused for identifying a particular UE and/or particular data to an eNB;to transmit uplink data to the eNB through CPRB resources of acontention based PUSCH (CP) zone; and to receive a hybrid automaticretransmit request (HARQ) response with respect to the UL data from theeNB through a physical hybrid ARQ indicator channel (PHICH); and wherethe CP zone is a resource area from which UL data are transmittedwithout allocation of an UL grant and wherein the CPRB resource and thePHICH is mapped to a cyclic shift (CS) set up based on the CPRBindication information.